Anyway, the story focuses on Johnny Rico (Casper Van Dien), but unlike the book, other characters get a decent share of importance to the plot. There's Johnny's high school girlfriend, Carmen Ibanez (Richards), who was never actually his girlfriend in the book; she was just a friend, even if it was obvious Johnnie would like to have been more, and in both the book and the movie, she was the reason he signed up for the Federal Service. In the movie, we actually get to see some scenes of Carmen's budding career as a starship pilot. Her trainer happens to be a guy named Zander, who was a rival of Johnny's on opposing teams of some football-like sport in high school. (Neither Zander nor sports played any part in the book.) He was also a rival for Carmen's affection. Meanwhile, another member of Johnny's team was Dizzy Flores (Meyer), who had a romantic interest in Johnny, though he just saw her as a friend. (In the book, Dizzy was a man, and someone I don't think Johnnie met until he joined the Mobile Infantry. Certainly there was nothing romantic between them. Also, Dizzy died in chapter one, whereas in the movie she's a major character throughout the story.) So... I gotta say one thing I liked more about the movie than the book was that women could be troopers in the M.I. So, while I can't recall exactly how I felt about Dizzy's sex change 20 years ago, this time around it was welcome, as was Carmen being more important to the plot. (Possibly Battlestar Galactica had something to do with my possibly being more open to characters' sex changing between different incarnations of a story, though I don't think I was ever particularly against it. At least not to the degree I'm sure some men are. Although I suppose part of it also is that the more opposed to a thing that misogynists are, the more in favor of it I become.)
Well, increased screen time for some characters means less of the plot of the book can be covered, I guess. Certainly a lot is left out and there are lots of details changed, and various characters are combined. Most notably, Lt. Rasczak (Michael Ironside) becomes more important by being combined with... well, I won't spoil which character from the book. But I will say he lives longer than Rasczak does in the book. We also get to see a little bit more of Carl Jenkins (Harris) in the movie than in the book. Still not as much as Carmen or Dizzy, but in a way, his character was probably the most different in the movie than in the book. This is because in the movie, a relatively minor concept from the book, that is, people with psychic abilities, was bestowed upon Carl. (In fact probably the visual I remembered most from the first time I saw the movie was Carl using that ability to read the thoughts of a brain bug near the end of the movie, so I was a bit disappointed on second viewing, because that felt a lot less important to me this time, after waiting for that scene to arrive.) Another relatively minor character from the book is another M.I. trooper called Ace, who has a larger role in the movie. A character with less importance in the movie than in the book is Sergeant Zim (Clancy Brown), though I wouldn't call him unimportant in the movie. I also want to mention some characters just because of the actors. There's Captain Deladier (Brenda Strong, from Desperate Housewives), and much more minor characters including a biology teacher played by Rue McClanahan (from The Golden Girls) and a psychic played by Timothy Omundson (whom I didn't know at all the first time I saw this, but immediately recognized him this time in the few seconds he appeared on screen).
And... man, have I even said anything about the plot, yet? Right... Johnny becomes a trooper, Carmen becomes a pilot, Carl becomes a psychic officer. Humanity is at war with an alien species of giant bugs. One cool thing about the movie is not only getting to actually see the Bugs instead of just imagining them, but also the introduction of a couple of varieties of Bug that aren't in the book. One very uncool thing about the movie is not getting to see the exosuits from the book, because the M.I. troopers don't use them. (It's also kind of weird that apparently they're still called "cap troopers," despite the fact that in the movie they aren't dropped onto planets from orbit inside capsules, but rather in drop ships. So the term doesn't make any sense, but at least it's not used often.) Anyway, as I mentioned before, a lot of plot points from the book are omitted from the movie, but also the plot points that remain in some form are often very different from how they happened in the book. And the progression of events is sped up a lot. And what was probably most disappointing to me (both times I watched the movie) was how little History & Moral Philosophy played into the the plot of the movie, compared to the book. (Although I do think that while my feelings about it in the book were mixed, in the movie what little we do see of the subject held no interest for me, and if we had seen more of it in the movie, it probably would have been entirely opposed to my beliefs. Then again, maybe the people making the movie kept out the bulk of the "moral philosophizing" because they believed it all boiled down to what little did appear in the film. And on that point I'd have to disagree.)
Anyway... I'm not sure what else to say. There's a lot of fighting and cool special effects and whatnot. So I think it's easy to see how I or anyone else could dismiss the movie as a typical, largely mindless action flick, and therefore deeply disappointing to fans of the book. And yet... as I said, it could be seen as satire, using the ridiculous pro-war propaganda to undercut all the battle scenes. But as I also said, it's easy to miss that, rather seeing the battle scenes as the actual point of the movie and everything else as just really bad writing, or whatever. Honestly, I think the satirical aspects of this movie are not remotely as obvious as the satire of things like The Onion. (So I don't hate myself too much.) Still... this is something I might actually want to watch again someday with the commentary track on (which is something I never do, and virtually never have any interest whatsoever in doing). I'm sure that would make the satire much more blatant, which could be fun. So I'll let you know if I ever get around to that.
There have been several direct-to-video sequels that I haven't seen and I have no idea if I ever will. There was a comic book that came out around the time of the movie, and I must have read one or two issues, though I don't remember anything about them. And there was a CGI TV series that I saw at least a bit of, which I'd definitely like to see again someday.