The first thing I ought to say here is that if you expect a similar film to the first Ghost In The Shell, you're going to be disappointed. However, if you want a more thought-provoking, visually involved film then you're definitely in the right place.
As I've said, it's not much like the first film. Although the plot retains the same pacing and tension, and the visuals are in the same style, the star of the previous film (the Major) is mostly absent, and instead the plot focuses on Batou, her former police partner. There is still the odd fight scene, but mainly this film focuses on what happens between the violence. Some people may find this offputting, but many will appreciate this change of focus, particularly in an anime film.
However, the film is not worse because of this. Innocence gives insight into a very different mind; this is reflected in the more philosophical plot, and bleaker locales. It develops characters in a far more subtle way to the original, which was fairly subtle already, and gives a genuine insight into the viewer's own life- more so than any other film I have seen.
The imagery used in Innocence is definitely among the greatest that I have seen. The blend of 2D cel animation and 3D CG materials is seamless and they always complement one another to a very high degree. The music is also used to great effect, and the ending theme suits the film perfectly.
Although this is very different to its predecessor, it is still a breathtaking masterpiece, which will stay with you for a very long time. If you haven't seen the original, or if violence is all that it takes to satisfy you, there isn't much here to like. But for everyone else this is a essential purchase.