This is what was missing from Pathfinder. I always hated the 'normal' level up system in D&D and Pathfinder. I prefer xp based leveling and more character customization and this book provides for exactly that. Sure, it's math heavy and a bit dry, but the work and thought put into this was incredible. It's a great system that offers alternate ways to design YOUR character, instead of just being a Fighter or a Cleric, you can do a lot more with this system.