In fact, as good reason number three-point-five, the acting of nearly everyone in the movie is rather good. Gary Oldman gets a lot more to do in this movie, and he does it very well, playing the one good cop in a city gone crazy and giving the audience a solid anchor. Aaron Eckhart, an actor I've never been particularly fond of, is really quite engaging as Harvey Dent. Of course, Maggie Gyllenhaal is a vast improvement over Katie Holmes, and Michael Caine & Morgan Freeman round out the cast with their trademark gravitas and a couple of light comedic touches. The actor I had the most problems with is sadly Christian Bale, who does a very good Bruce Wayne but grates on me whenever he's Batman, thanks to the ridiculous voice he affects whenever he puts on the cowl. You don't need to sound like you're gargling chunks of hot asphalt* to disguise your voice or sound intimidating. Less is more, man.
Bale's vocal antics as Batman are one of only a few minor quibbles, though. The story starts off as fairly straightforward but then gets as twisted and turned as it becomes more affected by The Joker's influence. There are many good moments in this movie that I could harp on, but it's getting late. The point is, even if you're not a comics fan but liked Batman Begins, I think you'll like this even better. Not that you need me to sell you on it. I just think it's worth your time.
* - Who am I