Very solid in Arena obviously you don't get punished as hard as Argus for 4 stats given the trade off is no Taunt. In a back and forth trading battle you can win the value game with a good hit.
This should be very close to Nesting Roc on rating they both require 2 minions for the effect, Nesting Roc is 4/7 and if Valkyr double hits it's 5/8 in value minus taunt with makes them very even in that regard.
Only major difference is you need some sort of board while Nesting Roc does not.
There's a big difference between restore 2 health and give +2 health. This card gives you a big board swing if you hit two targets, which darkscale healer can only do if you have minions that have already traded and survived, which is much harder than minions just being on the board.