A very well done book, Charles Phipps has a deep love for the super hero genre, and it is shown by the various homages to pre-existing comic characters and concepts. There are a lot of interesting ideas present here (Such as making the devil of the setting an anthropomorphic rabbit), and a great number groups and ideas that can be mined for existing campaign settings or played straight.
That being said, the product is not perfect; there are more than a few typos in the book, mostly in stat blocks, but that shouldn't detract from the enjoyment of the product (it didn't detract from mine), and also many of the characters don't have artwork (which can be kind of off putting if you'd like a visual medium for a character.)
Flawless? No, but its still a solid product and a great addition to any Mutants and Masterminds setting.