I played a Blood and Bone campaign with a few friends, and I can honestly say that this system and world is fantastic. I highly recommend that everyone who is a fan of d20 systems to give this a try.
Characters do not have classes and instead are able to acquire whichever upgrades that help flesh out their character. Upgrades include anything from having higher chances to intimidate someone, remembering how to lock/unlock any lock you have already picked, cleaving through enemies with huge weapons, or gaining the ability to raise the dead. You can make pretty much any interesting character with these abilities, and they all have a dramatic effect on your gameplay and strategy.
The system also has a great method for gaining proficiency in skills. Every level, you are able to gain proficiency in new skills or increase your proficiency in your current skills. Instead of gaining flat modifiers to your rolls, you instead roll additional proficiency dice (d4, d6, d8, d10, d12) along with the d20. I love being able to expand my characters to naturally learn new abiilties as they progress through a campaign.
While Blood and Bone has many great features, my favorite by far was the Tenacity system. When players do some wonderful roleplaying, the GM gives them a Tenacity (they also start with some at the beginning of a session). Tenacity can be used to gain advantage on a roll or to use a special upgrade ability. However, players can use their Tenacity on other players too! Some of the best moments in the campaign were when one player is in a perilous situtation and another player donates them a Tenacity allowing them to vanquish the foe.
All in all, I have a wonderful time with this system, and I will be playing it for a long time to come. I cannot recommend it enough.