I wouldn't call the movie pure entertainement, quite the opposite. It can be seen as that, but there are a few scenes that really stays with you if you've ever fooled around with drugs. The most obvious ones are when the narrator talks about San Francisco in the 60's, and when he talks about the "fallacy of acid culture" near the end. There's also something to be said about the "white rabbit" scene, though it's hard to put into words.