I don't recall seeing a SB halftime show that I liked as much as that. Actually, I don't recall any that I really liked...
Did I read it right, some here were questioning if his performance was live or not? I don't see they come up with that. Especially the vocals, nothing canned about that.
I liked the Shania Twain show a few years ago.
It's practically standard practice to lip synch outdoor perfomances like this. Another technique is to sing over pre-recorded music, especially if there is a lot of theatrics. IMO, Prince was "guitar synching" this time.