Yes, I mean it's less automatic. You have to attack to get your momentum
(Even with Mishima Zaibatsu out, if the opponent doesn't care for momentum, it might as well be a blank card.)
However, War Between Sisters and Mishima Zaibatsu Leader shut down PotE very easily. Actually, it's sad that it's shut down that easily, so if PotE is the game-changer that you say, then Air, Chaos, Death and Void just gained new staples. How about From the Mouse, Humility, which is Chain Throw E on a stick, also shutting down PotE?
Getting two momentum for PotE is only ever anything RESEMBLING easy through Death. Order and Void decks will die before they get the chance.
I'll wait until the next set drops to make a more informed decision, but as it stands, PotE would be a game-changing card if it were possible to play.