The first one I saw when I was 5-6 and it was the greatest movie ever, the other two I hated, I remember being like 12-13 and in the movie watching the second and yelling at the dumb asshole to roll around on the ground when the Compys started bum rushing him.
The third one was just on last night, it's really the desire of the director to incorporate characters in the movie that are essentially kids in adult bodies, and then adults and kid bodies. Although the kid wasn't that annoying, just less believable, it was the parents that you were rooting to get killed the whole movie, with no pay off.
The whole premise of bringing in tourists that, presumably the audience can relate to, completely staggering. The Unix girl was a small little thing right at the end, that I didn't even under stand when I was a kid (much less think I would actually be doing when I grew up), but all the junk in the 2nd one, just lacked any drive...pretty sure Spielberg slept through most of the movie and hated it the whole time, he doesn't even like sequels. The third one was just a bit less stupid, but forgettable if not regrettable. Between Dr. Grant stopping at his own peril to point out how smart Raptors are every time, with the enormous chubby he has for them, and just the dumbness of all the characters...every character has a moment where they just have to do something stupid and unnecessary and somehow one of the audience members is meant to relate to it.