Sum up:
Naruto: Ultimate Ninja Storm is essentially a fighting game (based on the first 135 episodes of the anime), with an explorable hub in the form of the Hidden Leaf Village (Naruto's home) between fighting portions. Unlike most fighting games, which take place from a 2D perspective, this game sets the camera directly behind the playable character, and allows you to move freely in all directions. The game mostly concentrates on one-on-one battles, with the main characters being able to call their friends in temporarily to attack their opponent. There'll be a total of twenty-five playable characters to choose from.

Recommended age:
The ESRB rated this game "T" for Teen, listing "Cartoon Violence" and "Mild Suggestive Themes." The "Cartoon Violence" will consist of fighting your enemy with your fists, side-kicks and ninjitsu (basically ninja magic), but there will be absolutely no blood.

The "Mild Suggestive Themes" will most likely consist of the story mode elements. For example, one male character is nicknamed "Purvy (pervert) Sage," as he likes to write romance novels and peek into the women's bathhouses, etc. So overall, I'd probably recommend the story mode for ages 10+ (as the story can be pretty intense)--but if you let your 7 year-old play fighting games, then I'd recommend the 2-player versus mode for ages 7+.