A great story, with hidden depth.
I found this game hard to get used to at first because it's not a shooter. It's a stealth game with interesting and varied ways of taking people out using gadgetry, scenery or simple brute force. I had been used to blasting my way in and out of tight coerners. The story is interesting enough to make you want to revisit the campaign more than once - the drug-induced hallucinogenic sections are quite mind-bending and actually make you question what is real within the game, which is a real achievement in itself.
Graphically it is stunning, but it is far too tempting to play too much of the game using detective vision, which means you don't appreciate the graphics enough. It's clearly evident that the unreal engine was used for the game, but the level of graphical detail on Batman and the main adversaries is stunning. I've seen this game now on the PS3 and played it through on the 360, and there wasn't really any difference, apart from the fact that my 360 sounded like it was having a hard time processing all the graphics.
The final set piece I found to be a let down however, and left me wanting more from the game. If you are a fan of superhero stories and comics, as I was when growing up, and have liked the recent glut of superhero films , you will be able to visualise the tenuous comparisons I'm about to make - This game would be better than the first Spiderman film, although not as good as Spiderman 2 (not to mention the joke that was Spiderman 3). It's better than the first X-Men film, although not as good as X2 (not to mention the travesty that was X3). It's better than Batman Begins, but not as good as The Dark Knight. I think you get the picture.
The voice acting and script is great, and adds to the great ambience of a great and very enjoyable game.