In my humble opinion, mash-ups are one of the best musical developments of the past five years. Why do mashups work so well? I'd like to remind you of that scene in "Ratatouille" where it is explained that one food (cheese, for example) and another (fruit) are perfectly good by themselves, but something entirely new and exciting and amazing when eaten together. Music works on the same level, I think, and this is a perfect example of that.
Heck, I'm not even a big John Schmidt fan, but this wowed me.