The Nintendo Wii Classic Controller game pad retails at most game Stores for around £14.99. The Controller Plugs into the Wii Remote and is mainly used for Classic Virtual Games which can be Downloaded via the Wii shop Channel.
The Nintendo Wii Classic Controller are Mainly used on the Virtual Console Games such as N64, Sega mega Drive, Nintendo's Older Systems and a few Other systems.

There are a few Virtual Games which will not work with the classic Controller but this is about five games and are mainly Commodore 64 Titles.

The Controller can also be used on some Games such as
The Legend of spyro the eternal Night (use the Wii Classic Controller like the PS1 Games of Spyro)
Mario Kart Wii (Use the Wii classic Controller like the Game cube Version)

Plus if you're a spyro Fan a new Title called Spyro Dawn of the Dragon Where you see all the classic Charters such as in the Pervious Titles of Spyro.

Overall the Wii Classic Controller is ideal add on if you have any old classic games or Wii Games which are Computable with the Wii Classic Controller Interface. so if you have any Virtual games or games which are Compatible I would advise you to buy one as there are only £14.99