based on the book

You know how sometimes you can read a book and actually "see" the movie of it in your head? (If you have no idea what I mean, play along and nod.) It's not necessarily the indication of whether a book is good or bad, but it is something that must be accomplished prior to say --oh, I don't know-- buying the rights to make it a movie.
That a book reads well visually in one's head does not guarantee that it will be a good movie. Most of the time you can create a visual of just about any book, some of those mental images don't translate well to film.
If film is difficult, imagine a live stage show. Nearly impossible. Yet just last year "Wicked" kicked some Broadway butt. I read Wicked, I'm betting the show is better. All of this musing is leading up to the fact that I'm reading E.L. Doctorow's Ragtime, and I cannot, for the life of me, figure out how they made this rich, twisted, quirky, era-defining story into what appears to be a schlocky musical.
Do yourselves a favor: read the book.