The movie is a pretty darned accurate rendition of the book. The dialoge in the movie is pretty dead on to the ravings of Thompson. The movie is based off the book, so it's none of this adapted from screen, using movie photo's for illustration crap. The artwork within the pages is pretty trippy in and of itself, and I highly recomend it.
I finished it in hours, but I read 700+ page books in the span of a day, so it's probably not a accurate read time for the masses.