I don't know the game well enough to comment on balance, but I do have to say that the Karma decks I've encountered are so non-interactive that they're not fun to play against. EZ/Karma seems especially egregious in this regard, as they don't usually even develop a board presence; they just nuke your stuff and typically hit the board leveled-up without any opportunity to fight against them being flipped. 

It's hardly unbeatable, but it feels like two people playing solitaire as you race against each others' life points and dismiss most of what makes the game fun.