It was only upon a review I saw on Spill.com that made me give this a try. I'm glad I did, cause this is now one of my favorite movies, and it's on par with anything Pixar has done.
This movie is wildly different anything Dreamworks has done before--no fart jokes or cultural references--just characters and a strong story. I can't recommend this movie enough, and there are plenty of extra features as well.
The only real question is whether to get the "Secrets of the Furious Five". I watched it and it's OK, but not necessary. It doesn't add much to the world of Kung-fu Panda and it's geared more toward children. If you do have children, this will give you some extra electronic-babysitter time for you dollar. Other than that, I'd say it's not necessary.