I have it and it is absolutely my FAVORITE 3rd ed book. It has eclipsed the Manual of the Planes. There is so much non-rules detail in there about dragon habits, lifestyles, society. I just love it. There are fully-statted out dragons of every variety and age. Great new feats for dragons (and dragon-slayers). I love the "metabreath" feats. You add some effect to your breath weapon in exchange for more wait time between breaths.
There's also lots of great artwork. Lockwood, baby.
Buy it.