Yes you pay 2 bucks extra for the glasses to see the 3d version. They are nice sturdy plastic glasses that look like sunglasses. No blue/red lenses. They are also showing a non 3d version. The movie is good and the 3d effects are pretty cool. I think you will enjoy it and the kids deffinately will.
All age groups I went to see it yesterday and the movie is great but make shore you see it in 3-D or else it's not worth it. Call the theater and ask before going.
I think all kids will enjoy it but only the older kids(tweens) will understand it. We took 4 kids ages 3-6 and they had no clue about the plot. However, it had enough action that it did not matter. The only way I can expalin without giving too much away is it is similar to the movie Back to the Future. We did not see the 3-D version due to the kids ages, so I am not sue about that.
My DS insisted on seeing it in 3-D. I was really concerned about the glasses, because cheap 3-D glasses give me a headache. Happy to report it was an incredibly pleasant experience. Like someone said earlier, they were reasonably high quality glasses - as sturdy as sunglasses.