Bought the bundle and played the DLC maps for the first time. Here are a couple quick thoughts:
Wasteland Bullet - I really like the idea: a series of rooms/platforms very closely placed, with connections across them. It's quite an unusual layout. Unfortunately, the environmental hazards are irritating (seems like you can't press jump too soon, or you'll just fall off without jumping). And the grey blur of the level is ugly as hell (and hard to parse) through a Scout cloak, even if you manage not to get smacked in the noggin.
Vekta Cruiser - Pretty good stuff, with the elevated walkways mixing things up. I also really like the middle area where you can see your enemies but not shoot them. However, it seems like the two side C&H objectives are too close together,
Beach Head - Awesome looking, with the rain and the water-logged craters and so on. It's a bit simple--pretty much just one big area--but the up-and-down contours of trenches and ridges and scaffolds keeps you scanning vertically. This reminded me a lot of the singleplayer, actually.
Southern Hills - Probably the best of the maps, since it has enough size and variation to let all classes be effective. And the nuke isn't so often as to be irritating. My only qualm is that it seems like the fort has too many machine guns, but that wasn't an issue yet.
Suljeva Cliffside - Like the twisty connections and walkways, dig the atmosphere, and the flamethrower is awesome to see in action. But I played a 32-player game and it was total chaos and the worst framerate I've seen online. Would be much better with far smaller games, I think.
Arctower Landing - I love how confusing the up-and-down staircases are, makes it much harder to predict the enemy. But all those stairs and doorways might make it too easy for C4 users to get kills. The objective placements seemed a little uninspired as well. It was hard to tell, though, because I was on a 2v1 game with a Japanese player, and at times we both had boltguns. It was mostly just really tight spawn bottling.