The best thing I can say about Tron Legacy IMAX 3D, is that it was worth the premium to see it in IMAX 3D. Unfortunately not all the scenes were actually in 3D, but those that were in 3D used it excellently. The 3D in this movie can go toe-to-toe with Avatar. As far as the movie goes, I liked it more that Avatar. It's not an "instant classic" but it is an enjoyable 2+ hours for the technophile crowd.
I throughly enjoyed Prince Caspian, and if you liked Disney's release of The Lion the Witch and the Wardrobe you probably will too. While it does take some liberalities, here and there, from the book it's a fairly faithful adaptation. It's rated PG but there's a surprising amount of violence in it (although it's almost entirely bloodless) so parents of younger children may want to investigate before they go. While the movie probably wont win any awards, it does have this going for it; I'm already eagerly awaiting the next movie in the series, Voyage of the Dawn Treader. And I suppose if it can do that's about all I could ask for.