I have mixed feelings about the super-crisp 48 frames per second/3D combo. Stuff that crisp always looks a little too "live" to me, like it's on the news. Especially when someone moves quickly. It's just not very cinematic.
However! That makes the special effects seem more real since everything looks live and more real. So it's a trade-off.
The 3D looked great. I especially liked when it was raining and drops would fall between the viewer and the subject.
[Spoiler (click to open)]Why didn't the birds drop them off closer to the mountain? Dicks.