Put me in the camp that prefers The Lost World to JP3. Both have their flaws, but I'll judge them by the quality of the real stars of these movies, the dinosaurs. One thing you can't knock The Lost World for is that it has some great dino action. Between the stampede, the Compies, the raptors in the tall grass and 2 T-Rexes, it had a lot of cool moments. For what it's worth, the CGI in this one is actually more impressive than the first film (as it should be, it came out four years later) and it probably would have won the visual effects Oscar that year if not for Titanic. As for the characters, Ian Malcolm was neutered in this one compared to the first, but Goldblum still makes it work. Plus, Roland is a badass. Yes, there are annoying characters in this (like the daughter, Nick, and Hammond's nephew), but nothing compares to how annoying the Kirbys are in JP3. God, I wanted them to get eaten. Tea Leoni screamed more than Lex did in the first film. And I've voiced my opinion on how I hated what they did with the T-Rex in III, but I don't really hate the Spinosaurus. I just don't think it's a suitable replacement for the Rex, and if it shows up in Jurassic Park IV, I hope it's nothing more than a brief appearance. I did like the addition of the Pteranodons. The raptors were okay, but I feel like they made them a bit too smart. And the CGI was not up to par. The dinosaur that smelled Grant and the Kirbys as they were going through the Spinosaur crap looked like it was straight out of Disney's "Dinosaur".
I think one of the things that has to be done in order for Jurassic Park IV to be taken more seriously is that nobody who's gone to either island in the past two movies can return to the island. It was enough of a stretch to get Malcolm and Grant to go back for the sequels. I'm open to cameos, just as long as they stay off the island. Nobody would believe that they would go back for more, willingly or unwillingly.