The concept is good but the controls were very difficult to play with. The process of piggy backing one battery on another effectively meant a lot of moving hands around as the buttons selected were hard to hit with hands in one place, so it was very prone to failure. Additionally, because the link between the batteries was near the bottom which made it very easy to accidentally break it if a battery is even slightly in from a ledge, having the connection up further or having a buffer would be a bit more forgiving.