1st edition Pathfinder's Blood of Angels covers their Origins and Birth (which covers their Childhood, Adolescence, their Physiology, their relationships with the other races, their view on combat, work, rituals), Geography (within the setting of Golarion), Living and Dying (which covers Old Age, Death, Faith, Friendship and Love, Art, Home), and Class Roles. There is a % table on Variant Aasimar abilities (which replaces their spell-like ability). While most Aasimar do not know exactly where their celestial powers came from, there is a minority who possess a stronger heritage to their Celestial ancestor. There are 6 distinct heritages in this book: Agathion-Blessed (Idyllkin), Angel-Blooded (Angelkin), Archon-blooded (Lawbringers), Azata-Blooded (Musetouched), Garuda-Blooded (Plumekith) and Peri-Blooded (Emberkin). There is a small selection of Celestial feats for the Aasimar, Aasimar-related features for Pathfinder's Oracle, Inquisitor and Cleric classes, the sorcerer's Martyred Bloodline, and a bunch of half-feats.
Blood of Angels is about 32 pages long. Definitely not a quick version of the Aasimar.