The game's length is a bit of a concern to. Though Co-Optimus has not completed the villain campaign yet, the hero campaign didn't take them very long, at all. They realize most of the value from the LEGO games in is the freeplay. Still, it seems quite short, indeed. If you aren't a fan of the villains, you'll be even more disappointed with the game's length.
However, the game is enjoyable, and there are many reasons to keep playing once story mode is completed. Adding a bit more excitement to the game (for parents, at least) is the fact that McDonald's has LEGO Batman Happy Meals. The toys in these meals feature codes that unlock characters and vehicles in the game.