I'm really in love with this game!
My only problem with it it's that it might result as being VERY VERY crunchy, if compared to D&D 5e, mainly because of its many subsystems.
I love it because it's at the same time a highly technical & tactical crunchy game, and a very narrative and character driven system, really the best of both worlds!
It's a complete overhaul of the 3.X d20 system. It's more low power and low magic if compared to PF 1 &2, or to D&D 5e, and to me that's a plus; more than that, magic is completely an optional element of the game: you can play a totally satisfying campaign even without any form of magic, or using just arcane or divine magic.
Mages and Priests are truly different from each other in the way they use their powers and spells, and martial classes have so many many cool and interesting options!
The Character Creation system is really flexible and customizable, a truly joy for players! As Ancestries you can play Drakes (small Dragons), Rootwalkers (Treants), and Giants, together with your usual Elves, Dwarves, Pechs (Gnomes and Halflings), Goblins, Orcs, Lizard Folk and Humans.
And there are A LOT of Classes non focused at all on combat, yet very very effective in game, like the Courtier, the Keeper, the Sage (or something like that...).
And you have ALL that you need in just two books: the Core Rulebook (which is a sort of Players' Guide, Gamemasters' Guide, Equipment Guide and Monster Manual all in one volume) and the Adventurer's Companion (highly recommended for half races, new feats and three different and very flavourful complete settings!).
Definetely a game worth checking it out, and the community at their site is really friendly! They produced also a fan made supplement pdf document filled with new classes, species, feats and much more!