I won't deny that the film is good big-screen entertainment, best enjoyed with a crowd, but as soon as the closing credits roll, the seams start to come undone. Given that we're talking abut flying superheroes, realism is not the primary concern (though I did like the way the first film made some attempt to ground things in our own world), but even so the timeline for some of the events seems utterly implausible: there's simply too much going on at any one time. While there are some striking visual images - that circling camera on the rooftops is quite impressive on the big screen, and there's a brilliant sequence where the lights shut down on Batman's lair - too many of the action scenes aren't sufficiently coherent: in one big chase scene, we're supposed to be concerned about the Joker's approach, but we never have the sense that he's actually in the same physical space so the menace is undercut.
Then there is the obligatory word about Heath Ledger's performance as said Joker. While his work is a fine bit of scene-chewing acting, all manic energy and wild mannerisms, it's also a very showy bit of work - presumably at the director's bidding - that seems to me far from his finest hour. I'd much rather remember him for his eye-catching work in the otherwise unappealing Monster's Ball or his exceptionally controlled performance in Brokeback Mountain. Or perhaps I'd best like to remember him as a high school kid in 10 Things I Hate About You, where he looks just like what he was: a kid off the plane from Australia who's just won the Hollywood casting lottery and is enjoying every second of the ride.