Minor spoilers ahead:
A book that started out strong, stumbled a bit, and ended okay. Not a bad book - indeed, it was quite enjoyable - it just hits a point where certain characters get on your nerves and it the story feels overly long, as if Michael Crichton was padding the story to meet the word count.
It was interesting to compare the book with the Steven Spielberg flick. There were differences, obviously, but it was fun to see what scenes made it into the movie. I like that in the book, John Hammond is far from being the nice, likeable character that the late great Richard Attenborough portrayed. In the novel, he's just an absolute b*stard and so blatantly out of touch with reality and the consequences of his actions (like funding the creation of dinosaurs and populating an entire island with them), that you'll almost gleefully enjoy his demise.
On the flipside, however, Crichton very obviously did not know how to write little girls. I say this because by three quarters of the way into the novel, you'll want to throw Lexi to the velociraptors yourself! In the movie, she's a fine, likeable character. In the book, she's almost a non-entity for most of the book whereupon she suddenly and inexplicably turns into an absolute brat. Seriously, there's a scene where she refuses to give her older brother (their ages are flipped around in the movie) a radio because "I found it first" and that trumps him needing to call for help. At that point, I started wishing that she'd either go back to plaintively complaining about being hungry, or that one of those aforementioned velociraptors would show up and eat her. Sounds terrible, but holy cow, she's bad.
All in all, I would still recommend this to anybody who wants to read a techno-thriller based on science run amok.