Its a kind of repetitive Pokemon Battle Revolution probably the boring game on the Pokemon series
Yes in the sense if you are a owner of the Nintendo Pokemon Games Diamond and Pearl, you will fully enjoy taking your trained Pokemons and importing it in the game to battle trainers from around the globe. So far this game it the only way to play with random people in the pokemon world (a obvious feature lacking in the handheld games).
But while it succeeds, it also fails cause the game fills of more of a $50 expansion pack to the DS games. If you don’t have a DS, chances are you would want to throw your wii motes in frustrations since you will have a hard time completing coliseums in single players as well as competing with a lot of Uber abuser in online.
So would you buy it or not, depends really on what kind of person you are. Pokemon fans would likely pick this up but if your not, stay away from this game.