Anyway, as everyone probably knows, the best part about BAA is the voice acting. It's great, there's heaps of it, and it works really well. Thematically the game is neat; touches like the Riddler having actual riddles (instead of exploding presents or other physical silliness) and Batman being dumb as hell are great. The plot literally hinges on Batman NOT hearing something the player can hear clearly and having to work it out later.

I'm playing on hard, and the game is proper hard; the way health works is neat as it returns with XP, so you don't generally actually run out but it doesn't come back automatically or require pickups (which amusingly are everywhere but Batman won't use them). The combat, however, is extremely boring, even against 8-10 guys. It's hard because you can't take hits, but the enemy combat AI is hopeless. However much fun it is to knock people off footbridges with explosions, it's not showing off the game very well.
The Metroid-em-up aspects are pretty broad, but pretty annoying. Your vision shows you a forcefield, with a wire going to a box... that you can't turn off/destroy/blow up/etc. Amazing!
The vision is also a no-loss situation. There is essentially no reason not to have it on all the time, whcih makes the 'detective' stuff pretty retarded. Amusingly, Condemned 1 and 2 actually had more sophisitcated detection. The vision reveals all the Metroid barriers and generally tells you what you need, which makes it less frustrating, but it's less successful than Shadow Complex's torch (whcih you at least need to point in the right direction).
I haven't finished it, and I probably won't. It leads you by the nose and while it succeeds as a very pretty and exciting episode of BAS, it's not really a very good game.