The game tells you straight-up what they are in bold text before you can bind yourself. You get perma-locked into being a kitsune and only have the most limited access to TFing afterwards, though Keros can 'reset' you if you want to change your appearance within that framework. You unlock a few new Power options based on your new race and more importantly, the way that every kitsune reacts to you will change now that you have such a visible sign of Keros' favor, as will the way the other gods react.