I quite like them. Also a couple of old pieces of artwork that people were iffy about have been made better, the first one that pops to mind is the Quickling, that is a evil looking little guy.
Of the stuff I've seen on the website, I prefer it to its 3rd edition counterparts. It doesn't seem to be the drastic change that we got from 2E to 3E, but it seems like its a bit of a slide away from edgy and back towards fantastic. I can't wait to see more of it.
Well, the cover might be the only weakness. There could have been better motifs (I think the quality itself is high, though).
I loved the art since I saw the preview books.
The Daily Art Preview Thread sometimes gave me the feeling that I don't understand anything about art, since there was some nit-picking going on, but well, I don't have to understand art. I just have to appreciate it, and I do, so far.
I dislike the idea of re-used art, though. But it doesn't seem very prevalent, judging by the stuff that was already shown in the preview books and the daily art previews by WotC. And if they keep to re-using good pieces, well, I won't complain.
I'm in the minority here, because I thought the 2nd ed. art was bland renditions of people in Renn Faire garb posing with silly swords. 3e art, to me, looked like nasty dangerous people with an urge to hurt things.
What I've seen is, IMO, mostly on par with the 3.* e as a whole; some of the stuff isn't as good as the 3e corebooks, but I haven't seen anything as bad as some of the art in the splatbooks. Also, thankfully little Wayne England.
The art is interesting - I love the out of focus backgrounds which give the piece a 3d depth, but it isn't my thing.
I prefer gritty, dirty artwork for fantasy stuff. Trudging through filth covered in blood and gore. Allot of this stuff, not all - I like the undead type stuff, is more like the kind of art you would get in some hairy fairy book of myths and legends written for young girls.