I went today with DD, age 5, and four neighbor kids, ages 6-9. I let them pick between 2D and 3D. Of course, they went with the 3D.
Normally I don't like 3D, but the 3D experience here was very good.
Positives:
* No blurriness.
* No obnoxious effects -- stuff wasn't popping out in your face right and left.
* They DID have kids and adult sized glasses at our theatre. That was a huge plus.
* The kids thought it was cooler than 2D.
This was probably my favorite 3D movie. That said, the movie/story would have been just as good in 2D. This movie doesn't really rely on 3D to make it good. It was just cooler that way for the kids.