This is a nice meaty product, presenting 12 subclasses and a clutch of new spells to accompany them. All of the classes are either converted from or inspired by AD&D kits and classes, and the author has done a great job of updating them to 5e. While I haven't playtested all of them I don't see any glaring balance issues, and there are plenty of options here that look like they would make for really fun characters. I'm a particular fan of the School of Astrology for Wizards, bringing a well-executed touch of Zakhara to the DMs Guild.
Chris, Loot The Room