Why People Hate It: Unlike the first two movies, Jurassic Park III was not based on a book by Michael Crichton or directed by Steven Spielberg. It had none of the legitimacy of the first two films. Instead of being an exploration of the possibilities of genetic manipulations and the responsibilities of science, it was just a movie about killer dinosaurs.
Why It's Still Good: Jurassic Park III is just a movie about killer dinosaurs!!! Let me tell you something about the first two Jurassic Parks. They kind of suck. The characters are flat, the plot is contrived and Spielberg doesn't do anything in them that he didn't do in Jaws. They're land shark movies, and Jeff Goldblum's monologues about science's moral obligations or Vince Vaughn's Greenpeace rants don't change that. I remember when Jurassic Park came out. It was a watershed moment in the infancy of CGI. We went to the movies for one reason: to see what dinosaurs really looked like. Sixty years of suspended disbelief with stop-motion animation wasn't cutting it.
Jurassic Park III understood this. It is a tight, simple story about a boy on an island of dinosaurs, and CGI had only improved since the first movie. Unlike those vaguely awkward, translucent ostrich-like dinos in JP1, these dinosaurs looked real, and there were lots of them. All the time. Call me a Philistine, but that's all I ever wanted from a movie about 21st century dinosaurs, and JP3 delivered.