I think I'll take my nephew. I was 7 years old when I saw it at the cinema and it absolutely blew my mind. He'll be 5 so a bit younger but I'm sure he'll love it.
Thinking of the 3D I actually think this film should work really well if the conversion is good. I'm thinking of scenes like the Raptor jumping up and snapping at Lex in the ceiling, the Gallimimus stampede etc. Wasn't planned for 3D but scenes like those certainly will look great.