For one, ALL movies should be in IMAX. There's simply no substitute. Regular 3D stinks. 2D stinks. IMAX is amazing.
My 6 yr old was on the edge of his seat most of the movie, and he thought it was awesome. M daughter is a big younger, but she stayed awake the whole time and said she liked it, but I can tell it may appeal to boys moreso than girls.
There are a few adult oriented laughs in there, but all in all, go see it.
Simply put -- wow. Wow wow wow. I loved the movie -- I was totally sucked in and loved the way it played out. I love the parallel with today and our own pursuits of technology and the balance of mother nature, the animals, etc.
I didn't even really realize how we had the goggles on -- it was just brilliant. I also loved how the movie started with a BANG right away...I will definitely be seeing it again soon!