I'm sure I've seen Jurassic Park 3 at least two or three times. I'm positive that watching it this weekend wasn't my second-ever viewing. I think. It's hard to tell - I knew almost every beat of the movie but I honestly can't tell if that's because of overexposure or because it's just so damned predictable.
Let's get this out of the way - the original Jurassic Park is fucking genius, I love it and you'll never convince me that it's anything other than a great film. Jurassic Park 2: The Lost World is underrated and a wonderful weekend romp - perfect popcorn. Aaaand Jurassic Park 3 is basically every late-night monster/adventure movie you've ever seen. It's not unbearably awful, just predictable (and therefore sort of boring) and not terribly clever.
I may be a bit biased - I've got a major crush on Jeff Goldblum and I think Laura Dern was just unspeakably cheated out of a chance to shine in the sequels, so JP3 doesn't offer me a lot of what I love about the first two movies. Sam Neil is tolerable, Bill H. Macy is utterly wasted, and Tea Leoni is nearly unwatchable. The two kids (handsome young archaeologist and actual child) are relatively inoffensive. The dinosaur design is awful. Which is a huge disappointment because fantastic monsters has always been the greatest feature of the Jurassic Park series.
Again, this movie isn't the absoloute worst. Not by a long shot. It's just vaguely entertaining, eminently forgettable crap that you can easily waste an afternoon on. But there's the catch: your time will feel wasted instead of well spent, and that's a bit of a downer when you're watching an adventure movie full of dinosaurs.