I don't really think Foundation holds up so much as its perfect light reading for teenagers. The dialogue style and lack of aliens (and romance) is highly original, if accidental. Its perfect for the sci-fi fan who thinks the movie 2001: A Space Odyssey is boring.

Later on readers can get into much meatier work like Herbert's, Bester and Bradbury.

Hmm..I need to actually read 2001 one of these days.