Before I go into the rest of the game, I should mention probably the biggest thing that sets this game apart from its predecessor (if you've somehow missed hearing about it by now anyhow) - the fact that you're no longer confined to your house, or separated from visiting other lots by long-assed loading screens, weird time jumps, etc. Now, the Sims have the run of the whole neighborhood. When they go to work, school, whatever, you can follow them around. You can have them go to whatever building you like in the neighborhood, go shopping, go jogging, find things to collect lying around... whatever. You can't actually see inside all buildings (such as the supermarket or book store, work and school), but instead deal with them through menus or what have you, but in general you can go where you like. Visit neighbors, be let inside their house, talk to people on the street, that sort of thing. The neighborhood is still divided by lots, and there's a bit of lag on slow old computers like mine, while the game has to put in all the detail on lots/houses as you pass them/enter them, but it's generally very seamless.
Hand-in-hand with this is a concept called Story Progression, which means that since you're living in one seamless interactive neighborhood, you no longer just jump between families and have time frozen everywhere else. Instead time continues to pass wherever you are, and the Sim families around you continue to grow and evolve as well. Families move out and move in, Sims age and eventually die, and have new children, who in turn grow up, marry, and so on.
This is where another of the problems comes in currently: story progression is a bit borked. For one thing, although there's an option to turn it off, that option is borked, and you have to fiddle around a bit with the game properties if you want to actually turn it off at the moment. For another, even if you play with it on, there are things that just don't work like (most people think) they should. Sims are often spawning random babies that have no other parent, even one that's not married to the mother/father. People are creating families and moving them in, only to have the created families move out. Switching between active families isn't as smooth as would be good, since you lose your inventory items, current wishes and opportunities, etc etc.
So generally... it's a good idea, and part of the execution is nice, and keeps things interesting... but it definitely needs to be tweaked.
Since I've talked about these in passing in both the previous post and this one so far, I'd better get around to explaining them, eh? These are kinda like fetch-quests for the Sims. You can have up to three Opportunities at once, one in each category: Career, Skill, and Special. These are pretty self-explanatory (except perhaps for Special, and I've only seen one of those at all, which had to do with bringing back a dead loved one). These show up either through a call to your Sim's cell phone, or pop up while at work. You can choose to accept them or turn them down, and if you complete one, you gain usually money, often a side reward such as added relationship points with a friend, and sometimes something special, such as (for gardening) the ability to plant specific plants that you normally couldn't in any other way.
The actual opportunities themselves may vary, and can be simple or complex, and fun or... boring. You may have to simply go talk to someone in town and choose a specific conversation option, in order to convince them of something. You might need to bake an item, grow specific produce, or do some other skill-related task and bring the end product somewhere. You might be given an item to deliver to a location during a certain timeframe. Things like that. Usually the more difficult ones have higher rewards, and as far as I know, there's no downside to failing them/turning them down (other than missing the reward).
These are fairly neat this time around. As I mentioned above, you still can't go into the work/school buildings, even though you can follow the Sim there and everything. What you CAN do however is click on a pull-down menu option below the work icon, and choose *how* you work (or do schoolwork). You can take it easy, which increases your Fun level and keeps off stress, but can lower your work performance (and maybe have some bad consequences if you do it too much). You can work hard, which lowers fun more and adds more stress, but boosts your performance. You can meet/talk to your co-workers, which helps you make them into friends without actually having to hunt them down and talk to them outside work (ugh). You can even work on improving the skill(s) that is/are tied into the job, or have schoolkids work on any homework that they didn't finish before school.
They've also changed how job promotion is handled. You have a meter on your Sim's career tab, and when the meter fills up, you get promoted (or get a raise, if you're at the top of your ladder. You can also get raises before that sometimes). Instead of having to have a specific number of friends/skill points for each job level, this time it just goes off the meter, which in turn is influenced by various things, which are also listed on the job tab. Starting off at a new entry-level job, it's usually just Mood that affects how you do. Later on things like your skill level with one or two skills tied to the job affect it as well, along with how well you get along with your colleagues and/or boss. And some jobs have another special thing that might have an influence as well, such as writing up stories or reports on people for journalism/law enforcement.
Pay is now by the hour, so you can go into work late or leave early, and have it affect how much get get paid (along with job performance, of course). You can even get part-time jobs now, to work after school for teenagers, although I'm honestly not sure if you can have a regular job plus a part-time job, if the times don't conflict.
There are also cool little things with various careers that make the jobs even more unique and interesting. For instance in some jobs like law enforcement and medicine, your Sim might be given a pager in their inventory at some job levels, and then be called in to work for an emergency, outside normal hours. From what I understand these calls are tied in to actual game events, such as someone having a baby, a neighbor's teen staying out after curfew, and so on. Law enforcement Sims get a free police cruiser to drive around halfway through the careers. Some careers give special socialization options, and law enforcement and journalism Sims can root through other Sims' trash cans to dig up dirt on them (and possibly get some neat things in their inventory as well). Culinary Sims might be given special food-preparation equipment that's better than anything you can buy from the in-game catalog. High-level musician and athlete Sims can hold autograph sessions at certain venues, and be paid for them. And so on, and so forth.
And since I'm talking about school and work, I might as well mention one of the nicest small changes that they've made: schoolchildren no longer carry their homework around, lose it, etc. Now it's kept in the child's inventory, and they pull it out and work on it from there, putting it back when they're done. Yay!
I suppose I'm jumping around a bit now, but there are just different topics to cover, and no good segues between some topics. ;) I thought it worth mentioning that the object interaction for the Sims 3 is also hella improved in general, as well as Sim-Sim interaction. There are less traffic jams, as Sims are smarter about going around each other (although they do occasionally still happen, and a queued task might be dropped due to it... but it's definitely less commmon). And it's much easier to place objects where you want them - now you can place them at half-steps as well as the normal whole steps on the grid, turn them to 45 degree angles, and things like that. So if you have diagonal walls in your house, you can actually put furniture against them! Like, OMG!
This extends to even smaller details as well. For instance, you can now put multiple small objects on most surfaces, rather than just one or maaaaybe two. If you have, say, a food processor on the counter, a Sim might set food down on the same counter top, just behind and beside it. You might have a multiple bathroom decorations on a small end-table to brighten the place up. You can put two items even on the edges of tubs - if you put bubble bath and a rubber ducky on the tub for instance it give a "ducky time" positive moodlet when you take a bath, and gives you the option to take bubble baths. You can put teddy bears inside a crib now, with babies. And one of my favorites: you can actually prepare food on corner counters, or use items that are set diagonally on them. Woot!
And under the same general subject, as I've sorta mentioned before, there are a *ton* of neat little interactions with objects added. You can upgrade items with the Handiness skill, perform new interactions, things like that. And a lot more things are like the lights in Sims 2, where you as a player can affect them, such as turning a TV on and off now without a Sim having to walk up to it, likewise a stereo or garden sprinkler.
The main thing to note here is that since job promotions are handled differently, you don't really *need* to do the socialization thing much anymore. Of course, it's still a part of your Sim's life, and makes some things easier and more interesting. And of course, if you want to marry someone/have a kid with them, you'll need to socialize. The thing is though that now you can not only invite someone to your house or talk to them on the phone, you can also bump into them in town, invite them out to a town lot, or maybe just go to their house to hang out. Lots more options, with the new neighborhood system.
This of course brings me to another new thing: the cell phone. Every Sim (past toddler age) now has a cell phone, which is an icon in their inventory. This can be used to call people to chat, invite them over/out someplace, call for services, throw a party, move out, call for pizza delivery, etc. You also occasionally get calls from friends, or as a random Opportunity. It's a lot nicer than the previous game, as your cell phone no longer wakes you up (unless maybe you have the "light sleeper" trait, haven't tried that yet). You also don't get 200185987 friends calling you up like "hey, I haven't heard from you, are you okay?" - you just get notified when a Sim you know slips down to a lower level of socialization (from friend to acquaintance or whatever). And even that's just a notice at the top right of the screen, instead of a phone call. Much nicer.
Creating a Sim:
I suppose I might as well say something about this as well before I'm done. This is another place honestly where the game falls down for me, and which took me a while to get past. For now at least, there are very limited options for things like hair styles - there's not even a curly hair option (just slightly wavy), there's very limited long hair for guys (and what's there is crappy)... blah. It sucks, when the game is so deep and addicting, and yet creating your actual Sim itself is so limited. And they're trying to sell additional hairstyles at the Sims Store, for like 50 cents to a buck each, which just... no. Bite me, EA.
Also, either I'm not used to creating Sims yet with the new creation tools, or they're just not... quite... right. Or probably a bit of both. It seems very very difficult to come up with a decent-looking Sim, much less an actively attractive one. It seems hard to move the mouth down low enough, to get a slimmer face, to get the right shape of things... meh. -_-
On the bright side, they've added some neat things, like voice options (three main "sounds" of voice for each gender, plus a slider to then change its pitch), and a ton of accessories. Now if they'd just fix what's wrong...
Aaaand.... I think that does it. I'm sure there's more I could say about the game, but that covers a lot/most of the big differences and gameplay options and so on. I could continue to blather on and on about other small details, like the fact that service Sims now alternate, are paid one lump sum, and differ in how well they do their jobs... or the fact that reading the newspaper every day tells you what happened the previous day in the Sim world... or the fact that there are weekly events that you can attend... or... or...
Well, you get the idea. So I'll just shut up now, thanks. ;)