We were offered the choice of classical races and this replacement in our group and everyone jumped on this. Why? Because it allows you to play the character you have in your mind, not just one of a couple premade races.
The possiblities are nearly endless, at the same time the trinity of biology, culture and choice prevents from building anything that would unbalance the game.
Of course, for the DM it can result in a bit more work as there are additional things that players might be able to do. On the other hand this can help in worldbuilding and creating your own npc races as well.
Disclaimer: I got my copy for free