The movie was great, but as some have said, the book was alot better. I wouldn't say it's so much "in your face" about drug use, as it is almost somewhat of a parody of the drug culture, a mockumentary of sorts.
Most of Hunter S Thompsons writings deal with the darker side of humanity, presenting it in a satirical fashion. I've read quite a bit of his works, FNL and The Rum Diary being among my favs.