Well, I don't think this charachter would work well in a typical game, but it's not unplayable. You could be akin to the stereotypical fledgling sorcerer who has great potential, but little current control over his powers. He could also work in a world where threats don't continue to get exponentially bigger, but where the challenge is more "realistic", i.e. the game is more about polotics, alliances, investigation, or anything but combat.
For a regular game, where power is essential, you might consider going 20-25 levels as one, then switching to the other.