I'm intrigued. There hasn't been a new type introduced since G/S/C, and an attempt to shake up the current type charts by giving dragons another weakness could be interesting.
Honestly though, when it comes down to it, whether or not Fairy will be a good new type is going to come down to whether or not it's going to be good for anything OTHER than hurting dragons. We know that it'll be super-effective against dragons, but what else? And what will resist it?
Competitive battlers have to take alot of factors into account when choosing which attacks to give their Pokemon, and the question is whether or not Fairy is going to be a better attacking type than Ice or Dragon.
On the flip side of things, how is it going to be as a defensive type? We know nothing about what Fairy resists or is weak to, and that's going to be critical in determining whether people are going to bother using Fairy-type Pokemon in the first place. I THINK I heard something somewhere about Fairies being weak to Poison, which could be an interesting way to make the Poison type a bit more competitive than it's been in the past, but aside from that, we don't know what to expect from them.
And also, there's the subject of the Magnemite-esc type retcons of Pokemon like Clefairy and Gardevoir. How will the Fairy type work in tandem with their pre-existing types? WILL Fairy be a good combination with Normal or Psychic?
So my only answer is that I'm intrigued. There simply isn't enough information about the type to form a really good opinion on it's merits/lack thereof, but I'll be paying attention either way.