Very good. Dragon Warrior will love this. And this is even more support for the taunt synergy cards. A buffed taunt with "Can't be targeted by Spells or Hero Powers" is going to be super annoying to deal with.
Good card. Good to generate from dragon-based effects. Taunt means it forces your opponent to interact with it too. I think it's going to be pretty great in slower dragon decks. (Paladin and Warrior especially)
I actually think in the current standard meta this is really hard to answer. No more vilespine, for example.