Odds are that, if you read the book first, you'll probably hate the movie. They really are totally different. Personally, I don't believe fidelity to the source is necessary for an adaptation to be successful. Plenty of films have been made that are slaves to the source and are terrible as a result! Great films are often made from bad books, so why can't great films just be different from the great books they're base…
I enjoyed the book, but was surprised by its unfashionable celebration of martial values: in particular a viewpoint about the necessity and inevitability of war. They couldn't possibly get that into a modern mass-market sci-fi action flick, I thought.
But Verhoeven did! And he managed to work in overlapping layers of both respect and criticism for the militaristic source material. He makes the jingoism and quasi-fascism alternately seem attractive, clownish, revolting, and necessary.
Preserving some of the book's rhetorical case for warmaking, even though Verhoeven also simultaneously mocks that case, is a subversive achievement as interesting, and in a way as faithful to the book's ideas, as a film featuring more of the "super suits" and infantry-tactics would have been.