Impressions:

Generally, games based on movies/cartoons or vice-versa are bad. They simply lack of action, storyline and gameplay. Besides that, they are developed by companies no one heard about them or companies like EA which gives **** games to all of us.
I played a lot of games like those ones. I am not afraid to admit it, but yes, I played them and they are bad. Some of them aren't even near the standards of a proper game. Check Iron Man: The Video Game. That's a really good example. Anyway, there is a game in partically which I liked it very much, and that's Spider-Man: Webs of Shadow. It had an original, great gameplay, no bugs nor glitches, it had some RPG elements in it and it was based on a famous cartoon hero, Spider-Man. If games which are based on movies/cartoons were like Spider-Man: Webs of Shadow, then the gaming world would've been better.
Now, it's Batman's turn to show up, and I have to say that this video preview really impressed me. Not many games have graphics like this one. Seeing these grahics made me think of how much video memory do I need to run it at full power on my computer. 128 MB? No away! 256 MB? Probably. 512 MB? Most likely. I am really sorry for my PC.
Graphics are great, but what about the gameplay? Well, seeing this preview didn't convinced me that there will be a proper gameplay. Not many "in game-footage" scenes. But I hope it will be great, because I trust Eidos, unlike EA.

Maybe the best part of this game is the storyline. Joker, Killer Croc, Mr. Freeze, Poison Ivy, The Penguin and even more emenies of Batman, all of them in one game and in which better place than Arkham Asylum. Joker is caught and sent there, and magically, he takes the control of the prison and makes everyone to fight against the Dark Knight (Batman duh!). The atmosphere is spooky and very sinister. Just perfect for a plot like this one.
I am really impressed with this game so far. The game looks like a proper one and I can see that it goes to a right direction. Batman: Arkham Asylum might turn out as a remarkable game and maybe the best game based on a movie/cartoon since Spider-Man: Webs of Shadow....or it might turn out as another **** game, which I'll throw it in the recycle bin. My advice is to still stay in touch with the game because it looks very promising.