I was constantly in awe of the real-to-life animation. The entrance to the dinosaur "land" underground was so beautiful, and I was blown away at how real the wooly mammoths' hair seemed.
My daughter is only 17-months old, but even she kept saying, "Wow!" She found it a little hard to sit still, as young kids tend to do, and I think it might have been in part because the screen was very dark at times and not always bright.
But, I thoroughly enjoy the Ice Age movies, and I think they're a great experience for kids of all ages!