I think the card is so cool. Agotcards.org has a preview of the new Jaquen H'Gar coming out later this month (in Chinese, but with English translation). I am a huge fan of it.
Link here: www.agotcards.org/news/v/23
He seems very fluffy in the way he works and he seems useful in the game, but not game breaking like the other one (which didn't work at all like I'd assume Jaquen H'Gar would work based on the books). I just wish this one had a way to kill people himself.
SPOILER
Now that I see him, I already want a fun deck that includes as many of the people on Arya's list I can get my hands on. Then I can kill three of them. Who cares about winning when I can recreate scenes from the books?