The three point challenge that was demoed by Bill Trinen and Reggie Fils-Aime at the press conference was playable. It controls very simply; you motion to your side with the Wii Remote and press B to pick up a ball, and then you go through the arching motion of actually shooting a basketball. It requires no button pressing besides to pick up the ball.
This specific game is all about the rhythm of going through the motion of shooting a basketball. The Wii MotionPlus is quite accurate and does an admirable job of replicating the feeling of shooting a basketball, but it lacks a bit of the tactile feel of actually shooting a basketball.
It seems to have the same pro and con that I think most Wii MotionPlus games have: It is realistic, but it can be very difficult to grasp at first.