Just got back. Fantastic movie. Some changes from the book to suit the screen. Some worked better than the book version of the scene, some less so. There's one half-scene in the middle of the movie that was truly horribly done, I think you'll know it when you see it, and there's a few changes to the ending that didn't entirely work... on the other hand, there's a brilliant moment in the ending there that'll get a giggle out of fans of the book. I think this version of Mars was less determined to kill Mark, actually.
Highly recommended.
Highly recommended.