The GN story is slightly different from the movie, but not so much that it changes anything I think. Also, I didn't spend as much time on the artwork as I usually do to really take it in and appreciate it. It's not that I didn't like it... it's just not the best I've seen and I was more interested in the story. To be fair the medium I used to read it isn't the best for that, but I'll be getting the proper copy soon, and then I'll spend some more time with it... I did get confused a lot by the characters, and I find that some characters' features changed during the course of the novel... irritating, but ultimately not a train smash ;)
Just rewatched the movie and although I think Natalie Portman was great, the whole time I was reading this I couldn't get Billy Piper out of my head as Evee... but a younger (Rose Tyler) Billie Piper.
I also realized how much they left out of the movie... I don't think it necessarily detracted from the underlying message, and I still love the movie, but I think the GN was better... obviously...