I miss Todd Lockwood.
I got a little Wayne Reynolds'ed out, so I'm okay with him just doing the covers.
But I'm not a huge fan of . . . well, a lot of the artists they use. The person who draws most of the dwarves with all their angular gear, for one. The artist who did the PHB races section eladrin picture. And honestly, the guy who does, like, all the rest of the art. You know, the one who did the dragonborn PHB races section picture, and the cover of Keep on the Shadowfell (sounds like "Keep Off the Grass"). He's technically proficient, but for about half his pictures I just don't like them.
Also, too much cleavage. Jeebus, I know it's fantasy, but could we be a little less generous with the "stab me in the boobs please" armor?
Worst art? The first big two-page spread in the DMG, with a group of PCs going into a cave full of monsters. It's almost Jeff Easley bad (Jeff Easley does terrible humans and cool monsters).
I will admit, I paid more attention to the art I disliked than to the art I liked.