I have read that it is the biggest pain to clean. The hole in the top is impossible to get into, and if algae grows on the side, good luck getting to it. It is also really difficult to catch fish, or remove dead ones. It is a neat idea, but somewhat poorly executed, at least for the price of the tank.
Remember that the tank your fish lives in is his or her's whole world. Ask yourself this question, and answer it honestly: would you choose to live there?