Lower and upper playfields can be great if they keep them simple, but also make the shots in there deliberate. I don't like upper or lower playfields where you just flip quickly or randomly to keep a ball going. AC/DC's lower playfield takes deliberate shooting and has no randomness to it. It also has a quick get in, get your shots in, and get out feel. Compared to something like the lower playfield in Congo, it's a night and day difference. There are some good and terrible lower and upper playfields in pinball. If they can make a game with three levels, and all three levels are good, that would be quite a feat and would be a lot of fun to play.