There were moments when Power Stone felt childish. The times when everything was "Go Team GO!!!!" got a little hard to swallow. Even though I only managed to play the PSP version of the game briefly (though I have owned it for 2 years now) I found the characters in the show were well represented in terms of their strengths and moves with respect to the game.
The whole show probably could have been shortened from 26 to 13 episodes, but it was still manageable to get through despite some short comings. I would recommend this show to people who are fans of the game, but don't expect too much if you are looking for a more solid story in your anime. In terms of the childish factor, I would have to place this series in line with Monster Rancher and Bey Blade. This show is clearly developed for the YTV kids (at least when I younger those were the YTV shows). Overall though, still worth taking a look at.