I saw it Friday with my wife and we both enjoyed it, a very enjoyable movie. However, I do not recommend seeing it in 3D, a total waste money in my opinion. Normally, my wife and I prefer to avoid 3D screenings but we went to the 3D because it was the next available showing, all other earlier showings had been sold out and even if they weren't we probably wouldn't have been able to get a decent seat anyway. Anyhow, back to the 3D, outside of some particle effects there was very little that stood out in 3D, nothing really seemed to come out of the screen anymore, nor did anything have any more depth to it. About the only thing that I think it really did was to make the helo with the CEO coming into the park look really fake, not CG fake but old Godzilla movie model fake, that helo looked like an RC toy that they filmed against a scale model set.
My only other real gripe about the movie was the intelligence of the I-Rex, once again movie makers making animals way too smart or more succinctly, confusing intelligence with knowledge. Just because you're super intelligent doesn't mean that you automatically know everything, you'd be able to learn things more quickly/easier and comprehend things that are unfamiliar to you but you wouldn't know about anything you never learned. One of the things was the tracking device, how did the I-Rex know what it was and that it should get rid of it when it escaped? It's never been outside of its enclosure so it's never seen the ACU team in action, never seen another dino escape and get tracked so how did it know what the tracker was? The biggest one was its thermal abilities, how did it know they were able to track it thermally? Unless it noticed that they were always to find it, for whatever reason, no matter where it hid in its enclosure there's no way that it could have known that adjusting its body temp would make it effectively invisible.
Aside from that, I really liked the movie. I thought it was better than both 2 & 3 and almost as good as 1. I just wished that during the ambulance scene they had one of the kids quote Jeff Goldblum from 1 and say, "Must go faster!".