Yes, Barry, I've been there (along with about 2 million other folks on Memorial weekend Saturday!).
It is an extremely well-produced piece of cinema, with a strong storyline (which may just be a bit too intense for very young children) and several laugh-out-loud 3-D tricks. Actually, the emphasis seems to be more on story than 3-D trickery, but it is still a very amusing attraction (watch out for the beer!!!). It is not quite up there with HISTA or ITTBAB (and the new Shrek 4-D is a different story altogether), but it is very well made, stars Christopher Lloyd and the theatre takes quite a crowd (about 600 a time, I think), so it shouldn't involve a long wait.