- the thing is not symmetric, you get a special Nunchuk controller for the left hand just like on the Wii
- the Nunchuk lacks motion detection
- the Nunchuk features L1/L2 shoulder buttons, a dpad and an analog stick, it also seems to duplicate the X and O buttons from the main controller
- the main controller has a large main button, only a single trigger, no analogstick and the four classic face buttons, Start and Select are on the side of the controller
- counting all buttons together it is the same number as on a regular PS3 controller
Update: Looks like Sony has no clue what they are doing. First they create a controller without dpad, without analogstick and without face-buttons that could be abused for directional control, then they develop a Nunchuk (officially called sub-controller) that lacks motion sensing and then they still end up demoing gameplay where the player needs two Move controller instead of the Nunchuk, see this and this.