I think the movie, as itself, was pretty good and entertaining. But it was much different from the book. The character of Natalie was supposed to, according to the book, look like "a fat Princess Diana". The actress was slim and pretty and scantily clad in the movie. Her attitude was pretty dead on though. And Hope, played by Gwenyth Paltrow, was supposed to have long black hair and be quite striking looking, The author compared her to a Native American in the book. Gwenyth Paltrow did not fit her at all, I thought.
Plus, the way they played his mom was that she was warm and fuzzy to him as a young child, but then went bonkers. I got the impression from the book that she was not very warm to him at all, ever.
And also the warm and fuzzy/her giving him her life savings scenes between Augusten and Agnes in the movie were not in the book. She was much more of a confused little mouse in the book.
But from what I saw in the DVD bonus features, it seems that the makers of the film (the guy that does NipTuck) worked pretty closely wiht the author to make things "believable". So maybe some of those things actually did happen, just were not written in the book.
So, to sum it all up, while the characters were not authentic, and some of the book was changed for the movie, I still thought it was worth watching.
Dh had never read the book but liked the movie alot.