I read the book, then saw the movie, and surprisingly enjoyed the movie. I wish the movie was longer; especially towards the end where he spirals towards permanent brain damage, and I wish they didn't combine the two characters (freck and fabin).
Of course, the movie was time constrained, and still hit on some of the major points, but I thought they left out too much (like the mindless druggies talking about microdot factories and a robot made up of hash makes it all the way up to canada..)