Starship Troopers was an incredible book. The technology and general descriptions he included were amazing, and the society he created seemed as if it would actually work. I think the first Starship Troopers movie caught the book's atmosphere perfectly, even if they did misrepresent the technology something fierce. (flamers and mini-nukes ROCK)

I really haven't liked the rest of the Heinlein I've read, though. Did he write Stranger in a Strange Land?