If you've ever played BG:DA or Champions of Norrath you'll have some idea of what to expect from Avatar. Though you start out with only Aang, soon you'll gather the other Benders to fight alongside you. You can switch to any character you like. The action is relatively simple, with one attack button, a block button, and some special Bending moves that use up chi. Slain enemies grant experience and item drops, and you'll become more powerful by leveling up and spending points to buy new Bending powers. Wash, rinse, repeat: fun ensues.
Avatar is a handsome cartoon and it translates well to the game. The cel-shaded characters look sharp, and have very expressive faces during the voiced cutscenes. The environments look nice too, and everything runs nice and smoothly.
It's nice to see a supposed kiddy game that aims a little higher, even if it's not yet on the level of some of the Capcom / Disney classics. Avatar is like an introductory course in RPG hack 'n slash, and its nifty cartoon license should make its lessons all the sweeter for the kids who encounter it.