The book is good and incredibly influential. It created the space marine, drop ships, and other things that have become staples of military sci fi.
I like the movie because it was done the only way it could have been done. It's almost a parody film, an ironic take on the book's fascist society. Similar to how Robocop, also directed by the same dude, is an ironic take on a lot of 1980s culture and news.