I'm also very impressed and excited for DFA. I think Ryan_Singer did a great job of explaining some of the great stuff that's in the book but I also wanted to point out some other things.
Most of the mantles work off the Fate System Toolkit -
Conditions (
http://fate-srd.com/fate-system-toolkit/conditions)
There's a pretty interesting section on creating Monstrous mantles as well as how to customize and make your own mantle.
There is an actual mechanic for being in debt to someone where you have to cross off the
Indebted condition and you have to work off the debt.
Scale is a new mechanic and I think is a great tool for the GM and players. The GM determines when scale applies; usually it’s when you’re using supernatural abilities. If you are supernaturally stronger than someone then you would have a higher scale than them and the same works vice-versa. Scale is ranked highest to lowest - Godlike, Legendary, Otherworldly, Supernatural, and Mundane. For each level of scale you have, you can have one of these benefits: Take +1 on a roll or an action, take an additional two shifts of effect after the roll if you succeed, or add an extra free invoke to an advantage you create.
These bonuses stack and if someone is two scales higher than you then they would get to take +2 on a roll or an action, take an additional four shifts of effect after the roll if you succeed, or add a two extra free invoke to an advantage you create.