The Incredible Maze is that it's cheap. The issue with The Incredible Maze is that while the play is fine, it feels like something quickly slapped together with middleware. The Incredible Maze doesn't feature particularly interesting visuals and would be a lot more engaging with a little more attention to textures, visual themes and music. That kind of attention to detail would also prevent minor issues like the fact that holes in the more complex mazes are often hidden behind walls. Since the penalty is so small for falling in, it's not a big deal, but it contributes to the general feeling that The Incredible Maze lacks polish.
For 500 points on the Wii, you're unlikely to regret purchasing The Incredible Maze, but nor will The Incredible Maze make a lasting impression.