When I got my 5e DMG, my girlfriend went through and stick-noted every boob/thigh/stomach cutout, as well as any other art that read "creepy male gaze" to her. Not a ton, but enough to make me feel a little sheepish and defensive. One thing we noticed was that, while protagonists had generally found a lot more clothing, the many of the female villains still wound up in something closer to fetish gear. I said, "this may be true, but you have to see it in the context of fantasy art over the last 40 years."
I recently pulled out my 2e PHB and realized that, actually, while there are 3 pieces of artwork that feel very much like "fantasy pin-up" (a wood nymph or dryad, the small naked woman with a tail kneeling before the grinning old wizard, and the monster with a tiny bikini and a long piece of cloth dangling between her uncovered splayed legs), most of the women shown are wearing real armor, without boob plates or cut-outs. I think the 5e artwork probably excels in that it more frequently features women of the various classes and races, whereas I feel like most of the women in the 2e book were part of ensembles. The binding for me 2e PHB is falling apart, so I'm afraid to open it more than I have to to get more detail. The 5e book definitely blows the 2e book away on racial diversity, but, stylistically, I have to admit that I like the 2e book much better. There is, however, a lot less art than the 5e book.
Overall, I like some of the 5e art a lot. I have to echo what others have said here, in that I prefer the DMG and Monster Manual art to the PHB art. There are some great pieces in there, and the diversity of characters represented is incredibly useful for my game, but a lot of the portraits are a little bland, and there are some real stinkers. I also really hate the downtime group shot around the campfire that some people seem to really like. It feels to me like a posed photograph that's meant to appear candid. Everybody is in the middle of some sort of action, but none of those actions seem to be related in anyway. The wizard is in the middle of saying something, but there's no indication that anybody is listening to him. One person is asleep. One person is warming her hands at the fire. And one person is staring straight into the 4th wall. Actually, it's a lot like the first 30 minutes of a D&D game with a new group of people. Maybe there's more to that picture than I gave it credit.
I generally dislike all the covers. They feel very GENERIC FANTASY ACTION!! in the way that always made me embarrassed to read my fantasy books in public as a kid. And the warlock or wizard on the front of the PHB is doing a very cheesy "show-off-the-legs" pose that feels pretty unnatural and something you'd never see a male character do in fantasy artwork.
I love the inside cover of the PHB. I love the 2 Turami fighters and the wizard. The warlock is great. I like the "characters identify items" piece and the woman in copper or bronze plate further on in that section. The non-portrait art tends to be very evocative. I'm digging that owl. While I can't remember much off the top of my head for the MM and the DMG, I remember seeing the Baba Yaga's hut piece from the DMG and thinking, "that's awesome."
So, it's a mixed bag. Some good stuff, some real stinkers. A little more consistency would have been nice. On the other hand, I love the way the art direction takes advantage of backgrounds, decorative items and sketches. And I think the overall consistency goes way up for the DMG and MM.