After seeing Batman Year One, I was nervous about this one, but I was pleasantly surprised! The story is faithfully recreated here, with very little censorship of the violence, and most of the (included) dialogue straight from the pages of the comic, albeit with some forgivable changes. The pacing is excellent, and really captures that sense of "awesome" that the graphic novel had. The visual style is "close enough" to Millar's work to give you flashbacks, but of course it lacks the detailed nuances of the comic. And lastly, the music fits everything perfectly.
Some complaints, though. First and foremost, the acting lacks passion. Virtually all the main characters play "middle of the road" emotions well, but any extreme was unconvincing to me. It's almost like there was a "no shouting!" rule for the actors. Nobody gets really angry, or forceful, or upset. Even so, it's nowhere near as disappointing as the acting in Batman Year One.
Also missing is Batman's inner monologue- which I guess can be forgiven since movies are a visual medium, but ultimately we lose some of the comic's best lines because of it. Though they do try to force some of batman's narration into the movie as dialogue, it doesn't work that well at all.
One change I'm not sure about is the PG-13 censorship to the script. They maintain the political dichotomy that existed in the comics, but it's way toned down. They seem to want to avoid alienating people on either side of the political spectrum (perhaps wisely). Some of the humor is still there, but again, it's got kid gloves on.
In the end, though, this is a wonderful execution of a great story. I eagerly look forward to Part 2!!