Beautiful movie, in every respect.
Madhouse really outdid themselves with the animation on this one. The art style is also very reminiscent of Tezuka's work, even though he had no part in the film. It is cartoony, and you think that such a style would drag the film down. Not in the slightest. The backgrounds are stunning as well.
The soundtrack was also fantastic. In fact, I'm listening to Metropolis
right now. The music helps define the setting, and it just plain good music.
As for the plot, it was pretty much what you'd expect it to be. This is entirely justified, considering that the original work (that is, the 1924 movie the manga is based on) introduced most of the tropes at work in the film. Fortunately, the movie doesn't fall prey to the pitfalls of these tropes and manages to keep the viewer interested.
All in all, this was a very good movie. In fact, there are a few people I need to show this to.