Well the initial premise was interesting as it tied to an old plot element. It also explains how exactly Gildarts ended up with Acnologia. Always found it weird he ended up encountering him, but considering he was on a dragon hunt, I can imagine he was tracking any rumor he heard about dragons.
That there's a sub plot going on in the guild is also nice and I'm intrigued by the White Mage thingy and how it will tie to the story.
That said I have mixed feelings about the main story. Dragons are supposed to be extinct and Acnologia was supposed to have been the strongest of all, but then there are apparently 5 equally strong dragons? That they are on a different continent, shouldn't make much difference. And then for some reason they are not allowed to speak to anyone about these 5 dragons, but they have to destroy them despite the dragons being seemingly dormant? And to top it off they come into contact with a guild of dragon eaters as, again, dragons are supposed to be nearly extinct, but there are enough of them to nourish an entire guild? And how where they initially able to kill a dragon? Heck even with dragon slayer powers, it was shown it was nearly impossible to kill dragons, but they make it seem like it's a cinch.
The dragon-types magic are cool though.