Trakt for iOS
Works on iPhone and iPad.
It wasn't awful, but, I think I must be the only person in the world who didn't think it was great. There were times when breaking out into song mid-conversation without some sort of elaborate set-change didn't make sense, The 2 leads weren't exactly talented singers or dancers -- no wow numbers. The sets improved by the time the final number rolled around, but the singing and dancing remained an afterthought.