The movie kept moving along both in action and laughs. There were younger kids who were scared by the dinosaurs who could still be heard crying and screaming even after the dinosaurs were gone. I would not recommend this movie to kids under 8 for this reason.
The 3-D effects were subtle and not in your face like some 3-D movies. You almost forgot that it was there, but it definitely was an enhancement that was nice.
The entire family enjoyed it, and I liked it much better than Ice Age 2. They also featured some deft adult jokes that the kids missed-like inside jokes for the parents.
If your kids are older and love the series it is fun movie to see...