Book review of Starship Troopers I posted on Amazon.com
This is totally different than the movie, but only in good ways. Heinlein is a expert of political philosophy applied to science fiction and paints a world of a fascist government that is embraced by its citizens, and you can sympathise with those citizens and see how they view it in a positive light. I love a book where you can see things from outside of your own perspective and still relate to the characters. It also allows you to see the current direction our world is taking and how external military threats can shape a nation, and how the shape of the nation can help generate those external threats.
Oh, and yes, space marines go kill aliens. That is fun too.
If you end up liking this, go pick up The Moon is a Harsh Mistress. In that, it shows how a revolution based on libertarian virtues breaks out on the moon and overthrows a repressive government. They aren't at all in the same story line, but in some ways I feel it makes a good follow up.