I did get legend with this deck last month. i must admit it took me a while :) But i had alot of fun. Luckely the losses go pretty fast.
Against green DK it is very hard to win (and fast Pala). But againt the rest it is very possible. The best tactic againts those fast agressive decks is to ramp asap, even if it will cost you alot of hit points. And hope to survive the next few turns and than stabilize. If you try to fight too early it often goes wrong, since they refill the board anyway. We need those manathirst cards to be online.
Againtst non-aggro this deck is very stong i think. Against aggro, yeah you better play some other deck if your main care is winning the game. And since most players play the same boring aggro deck, yeah I can imagine the frustration :)
If you only played a few games, maybe give it another try. Sometimes you just lose 5 in a row. The green DK skill level is high among the player base!
I like to have fun, and this deck is fun to me.