I first read Starship Troopers when I was 16, and since then I have always come back to it. It is full of quotes and relevant philosophy for our modern age. The average reader takes only the seemingly fascist overtones that are present in the book, but they do not see the deep analysis of why the current system of rule works. There is a specific passage where an instructor in Juan's O.C.S. informs the class that during peacetime, most of the veterans that come from the Federal Service (and have the right to vote in Heinlein's world) are not soldiers, but rather come form the non-combatant auxiliary services. This key point is often overlooked in reviews that paint the novel as a fascist war utopia. Heinlein uses the science fiction genre to explore pressing philosophical questions with his novels, and Starship Troopers is no different.
This novel asks the reader to do a lot of thinking about their beliefs and philosophy, especially about the concepts of humanity and citizenship. I think that everybody should read this novel, especially those who consider themselves "liberal." Often times I have found that many people take being a citizen of the United States for granted (especially liberals, but some conservatives as well). There is not a glorification of conservative values here, just an examination of what it means to be a citizen of a government and to serve your government. That's the reason the U.S. Marine Corps has this book on its required reading list for O.C.S. students.
I personally really dislike the movie. Verhoeven destroyed a great novel with his arrogance and lust for sex and violence. The only redeeming value in the movie is the special effects. Hopefully in the future a director will want to tackle the challenge of bringing powered armor to the silver screen.