"Starship Troopers" opens with a 1950s-style recruiting film, asking the audience what they're doing to serve the human race. Fresh-faced troopers turn sharply to the camera, exclaiming, "I'm doing my part!"

That recruiting film is just one of the many differences between "Starship Troopers" the movie, and Robert Heinlein's classic novel. There are others, immediately noticeable to anyone who's read the book: female front-line soldiers; nifty power armor replaced by grunt uniforms that look like they were lifted from the set of Fox's short-lived series, "Space: Above & Beyond"; bugs that have eschewed guns in favor of more primitive (and bloodier) weapons. If you go in expecting a loyal adaptation of Heinlein's book, you're going to be disappointed.

On the other hand, if you go in expecting an action-packed bug hunt full of gore, violence and stunning special effects, you're in for an immensely satisfying ride. At least half a dozen separate special effects houses worked on this film, including Tippett Studio, Banned From the Ranch Entertainment, Sony's Imageworks, and the granddaddy of them all, Industrial Light and Magic. This amassed talent has given us several planets' worth of nastily real-looking bugs, gorgeous (if somewhat cliched) spaceflight sequences, and, um, enough anatomically correct dead bodies to fill Arlington National Cemetery.

The battle scenes and effects work do their job handily -- that is, the job of distracting us from the lack of character development, convincing dialogue, or in most cases acting on the part of the cast. Then again, in a movie like this, acting isn't really required, and as with Will Smith in "Independence Day," talent shows itself in spite of the script, not because of it.

There are some familiar faces worth noting here, though. Dina Meyer, playing a Dizzy Flores who was apparently transgendered in the transition from book to film, will be remembered by those of us who sat through the travesty that was "Johnny Mnemonic" a few years back. But as far as young-gun performances are concerned, the one to watch is Jake Busey, who plays a wiseass Ace Levy in this film, and also did an entertaining turn as a fanatical terrorist in "Contact". Of all of the cardboard characters in this film, his would stand up longest in a heavy downpour. And then of course we have Doogie Howser, uh, Neil Patrick Harris, as Carl. I was kind of hoping that the movie would be true to the book just this once and kill him off, but `twas not to be.

The story, as one might expect, is thin; there's just enough plot to hold the characters together from their first appearance in a high school classroom, listening to a watered-down version of one of Dubois' lectures, to the comrades-in-arms finale -- barring a few messy losses along the way. Most of the major events from the book -- the assault on Klendathu, the destruction of Buenos Aires -- are still there, although their significance has changed. Also as one might expect, the film isn't as subtle as Heinlein's novel. Instead of supporting a point more considered than "the only good Bug is a dead Bug", the battle scenes are the highlight of the film, and Rico's (an altogether too pretty Casper Van Dien) motivations for joining the Mobile Infantry in the first place, and for changing his mind about resigning halfway through his training, are much simpler and easier to understand. (Rasczak's (Michael Ironside, gritty as usual) death is also much messier and a lot less meaningful than it was in the novel.) The script is, on the whole, pretty unremarkable, and mainly serves to set up the bloody but superbly executed confrontations between the humans and the Bugs, although Sgt. Zim's (Clancy Brown) repeated calls of "Medic!" are pretty funny.

Devoted Heinlein fans are already calling for Verhoeven's blood. It's not surprising, given the strength of Heinlein's following and the fact that his vision, whether you agree with it or not, was largely sidelined in the film. (The detail that federal service is a requirement for citizenship was left in, but unlike the novel, no argument is made in favor of or against this method of enfranchisement.) The lectures from Rico's philosophy instructors, for instance, are reduced to a few minutes of celluloid near the beginning of the film, and those moments are chiefly used to set up a rather flimsy love triangle (later conveniently dissolved by the untimely and indubitably nasty death of one of the parties involved) instead of making any point about military service as a requirement for citizenship and/or the propriety thereof.

However, there are a few things about this film that the book doesn't have. One is a more global point of view. In the book, everything we directly witness is through Rico's eyes. On the one hand, this serves to bring home the experience of the guy on the ground, an experience most of us will never have the opportunity to share: you do your job, and if you get killed it generally comes as a surprise.

In the film, we get another point of view, that of Carmen Ibenez (Denise Richards), who not only makes the grade as a pilot but garners a reputation as a hotshot. While her screen time mostly serves to set up some lovely spaceflight shots, it's worth noting that it does emphasize an interesting aspect of the relationship between these two characters, an aspect that was only tangentially addressed in the novel. Carmen knows what she wants, and gets exactly that, while Rico is thrown into a situation that he's in no way prepared for. In the end, they both have to deal with the (bloody) results, although they do get a sunset ending with Doogie Howser in tow.

But that's about as deep as the movie gets, and the main things we learn about relations between the sexes in the future are 1) prom dresses are just as ugly then as they are now, and 2) women might make the grade as front-line grunts, but romance is still a requirement for a satisfactory existence (not to mention that the naughty girl still gets killed). If anything annoyed me about this film, it was that we never learn why Dizzy Flores joined the MI, but it's okay because she gets the man of her dreams before biting the big one.

Am I complaining that the end result of Verhoeven's efforts is a far cry from the novel Heinlein wrote? Not at all. Hollywood rightly deduced that an attempt to explore the underlying themes ofStarship Troopers: the novel, would most likely end in commercial disaster. Instead, what we have is a sci-fi action film full of elegantly brutal battle scenes and unmemorable dialogue that doesn't detract one iota from the roller-coaster thrill ride of this film.

All the same, I could have done without the Brain Slurpee.