For the record, "World of the Elderlings" is something nice and brief I'm using as shorthand for the Farseer, Liveship Traders, and Tawny Man trilogies. If you want the individual book titles, I'm sure you can look them up on Amazon. ;) (Yes, I'm being lazy right now. Did I mention I'm also tired? But I will persevere!)
So in a nutshell (heh, I crack myself up. Okay, maybe not), I really (mostly) enjoyed the Farseer and Tawny Man trilogies. There are some characters in both of these that I really like, which is the main draw really. That's not to say that the writing or plotting is bad, because both are also good, but the characters were even better, for me.
The world is also one of the big draws, as the more we see of it, the more detailed and fully-realized it is. There are a few things that I think a bit... er... silly for lack of a better word, or perhaps "hand-wavey" or "convenient" would be a better choice of words. But not much, and for the most part it's a huge draw.
There are a few drawbacks though, like the, ah, wonky moral compass of the main character, which forces me to distance myself slightly more than usual from him upon reading, but it's not so terrible that it made me, say, not want to read anymore. Also, it's hard to imagine reading some of the books as single volumes, since they're so directly tied in one to another. But hey, who wants to read only one out of a trilogy, anyhow?
The Liveship Traders trilogy was... also one that I read fairly fast through (after both of the other two, even though it came in the middle, so a few very small things were "spoiled" but were more interesting to read that way, perhaps). But at the same time, it had more problems, and wasn't as overwhelmingly good in my memory.
The main problem, as the main strength in the first book, would probably have to do with characters. First off, she was juggling just too many main viewpoint characters, not a *huge* amount but enough to be annoying when she'd get one to an interesting point, then cut off to the next, and you'd know it'd be a good chunk of book yet before you got back to that other point, by which point you'd have had the intricacies of the plot swept under what else you're reading and trying to remember. This is probably a minor gripe, but it's an irritant.
The bigger character gripe though is that I came dangerously close a couple times to uttering (or at least thinking) the eight deadly words because of some of these characters. (Thanks prince_corwin for reminding me that it was eight, specifically "I don't care what happens to these people" - I was turning "don't" into "no longer" and making it nine.) None of them went *exactly* that far, but some of them were walking the line. And then when some of them became less... annoying, the shift in their character was a bit too sudden and not really realistic, to me.
Luckily some other of the characters were less ambiguous, and I could enjoy them more whole-heartedly. But in the main, I'd say for this particular trilogy the draw was visiting this other portion of the Elderlings world (and it does get quite a bit more fleshed-out due to this side trip), and in seeing how the story would come to a close. So I guess overall I'd still say this trilogy was positive, but not as much so as the two trilogies that sandwich it.
So short-short version: These books are definitely suggested for fantasy readers, especially those that enjoy and appreciate creative world-building, but the middle trilogy is less whole-heartedly endorsed.
Oh and damnit, for a quick spoily speculation... I AM a bit annoyed that she plays so damn coy with whether The Fool is male or female. Or both or neither, for that matter. I suppose in the long run it doesn't really *matter*, but... he/she's probably my favorite character out of the nine books, and I want to KNOW!