This is Woody Allen's brilliance without the self-absorbed neurosis, and the closest an American movie is going to get to European sophistication and non-formulaic plotline. It's definitely adult, so send the kids to a different movie, and then enjoy. The dialog is pitch-perfect, even though at times you can almost hear Woody's own voice. The movie is engaging from the start, but once Penelope Cruz shows up it just skyrockets to a whole new level. It's so refreshing to see characters that are fully human and not interchangeable Hollywood plot dummies.
Good as an action movie, terrific acting. Jack Nicholson is a hard Joker to follow, but Heath Ledger aced it. The entire cast was a pleasure to watch. Unless you are totally violence-averse you will want to see it. I do think it didn't need to be quite so long, and if we're going to be in the comic/superhero world, can't we have a bit more satisfying triumph of good over evil? At the end it seemed like yes, it was over, but did the good guys win? Not so clear. And did we really need to introduce a second quasi-villain at the end. Did he die or what? I didn't mind extra time in the air conditioning, but there was too much plot and too many bad guys. Why did we care about the Chinese guy again? It was reminiscent of some James Bond movies where it reaches a climax, but then, whoops, we're still going.