Different to manga and anime, but a good movie adaptation.
Sure it doesn't have the sex and ultraviolence, but I thought the director really did the core premise of Gantz justice.
Basically, he stripped back a lot of the more controversial stuff (which worked better in the anime/manga anyway) and made an accessible, stylish feature film out of a confusing premise (seriously, try explaining what Gantz is about to someone...).
People who loved the anime/manga seem to bash the live-action movie, but they have to realise that Gantz can't work on the same level in every form of media. Concessions have to be made, and the live-action film doesn't concede enough to be a bad film or ruin Gantz.