Updated January 22nd: read my full review of SW CW: Lightsaber Duel here

Sum up:
Star Wars the Clone Wars: Lightsaber Duel is based on the CG show on Cartoon Network, and has you fighting (in single & multi-player) as iconic prequel characters (like Obi-wan, Anakin, Count Dooku, General Grievous, etc.) in many of the enviroments of that mythos' settings (such as Tatooine, etc). The Wiimote is used to control the characters' lightsabers; if you swing it left, right, or jab it forward, the character will do the same, and you have control over the force by flicking the nunchuck.

Recommended age:
The ESRB rated this game "T" for Teen, listing "Fantasy Violence." This obviously refers to the playable character fighting with lightsabers, flinging objects and each other with the force. But beyond this, there is no reason why this game should be rated "T" (I think "E10+" at most); if you let your 10 year-old play Super Smash Bros. Brawl, and they like Star Wars, then I see absolutely no problem in recommending this game for ages 10+ (although the single-player campaign mode is too difficult for kids 7+, they could easily play this in verus mode with siblings, parents, etc).