It's fantastic, but it's not a light read. It's dense, it's beautiful and it adds a lot more to the story than the movie had time to tell, including some of the aftermath. I would absolutely suggest it if you have the time to take it all in.
Some believe it's more complex. The ability to replicate it into a movie was hard they believed, but hopefully the new anime would be more precise and as good as the manga's ability to relay information.