While not the best movie (3 stars from me), it is still a lot of fun and is worth seeing, especially if you liked the first Thor movie.
It was in Real 3D format, but they didn't play games with gratuitous 3D effects just for the sake of doing them.
The basic story is the supposedly defeated and long dead Dark Elves are back and are trying to reset the universe to their standards.
Thor, of course is trying to prevent this. The story spans the nine worlds and there's a lot of world jumping.
There's also quite a few chuckles. Stan Lee does make a cameo, I'll let you find it.
Oh yeah, stay until the VERY end, after the credits.
There was also a trailer for a new Captain America due on 4-4-14. It also looks like fun.