I find I can re-read the book very easily, just sit down one evening and before I know it its all over (again).
The movie had things like the music and Circus-circus set that are nice to see and hear - even when you've already imagined it all fitting together. The "wanna buy some heroin!" scene is actually much funnier in the book.
I was recently thinking about the <a href="http://www.obviouspop.com/gonzo/images/gonzotheart.gif">incredible original Ralph Steadman illustrations for Fear and Loathing</a> and what would have happened if Steadman and Thompson had collaborated with the masters of anime and western animation to make the movie.
Freaky thought.