Overpowerness of any deck is determined by overall win/lose ratio compared to other decks, not by the fastest winning possibility.
I guess, my new blitzkrieg deck (frenzy+overpower+legends+swifts+death wave+ vampire)is one of the reasons of this thread.
Now it is really possible to win very fast:
http://i31.tinypic.com/34ywimo.jpg
http://i27.tinypic.com/w2ep6w.jpg
but reverse of the medal is that you almost never can win with it if opponent survived 20-30 rounds.