It works okay but it's by no means comfortable holding your controller like a wheel for a long period of time.. Anyone who can beat someone good with the sticks with motion steering ill pay them $100.. AKA not happening.
I played 6 hours with motion control yesterday. Yes I can't lay down lazy on my side in the sofa, I need to sit up more straight to hold the controller vertically. But racing goes a lot better IMO, much more precise steering. At some point my right wrist seemed to get a bit tired but that might just have been due to my seating position.
You don't have to hold it like a wheel. Hold it like you would playing any other video game and lift up the sides to turn.