The book is really a science fiction thriller. It has an ingenious premises of people bringing back dinosaurs to life through genetic engineering.
There are a variety of flaws to the book. The one that I found personally most annoying was the character of the mathematician Malcolm. Malcolm throughout the book pronounces on why the park is destined to fail based on the then hot mathematics of fractal theory. A lot of his arguments are so generic that they could be applied to any new endeavour to show that it was bound to fail. He is meant to be prophetic, but he is just an annoying character spouting hokum.
Crichton's palaeontology is good. Especially, because he makes the perfectly correct point that a lot of what we think we know about dinosaurs is bound to be wrong. When he deviates from the accepted view he notes it.
The biggest flaws are however the general stupidity of the character's actions. No one acts with any sense at any point and the very straight forward writing style. In a book like this one does not expect masterful prose, but it is so simple and straight forward and grade-8-reading-level-ish that it takes ones breath away. In particular, there is nothing of interest done with the dinosaur descriptions and the book fails to invoke the wonder and awe of the creatures, something that the movie successfully did.
The merit of the book is the premise. The idea of bringing dinosaurs back to life as a tourist attraction is a delightful one. That they run amok is to be expected and the running amok is only done OK.
The book in the end is a piece of trash, but it is a piece of trash with one of the most endearing premises ever, so it gets three stars from me.