Comparison to hero power is quite good actually. But when thing should not be forgotten. You get a hero power and -1 card. It reads as give 0 mana your hero another hero power and use it for 2 mana. Also not usable unless the minion dies.
Also this card ---> the first artifact in hearthstone. How can you dislike that?
It was the 1st LoE card that I tried in quite a few cards (I even got it before release due to the bug & they deactivated it some hours later). Fun, especially when you think of all these creatures wearing hats (!!), but not something game changing or efficient, in my opinion.