Summary: DDR Extreme is all wrong. Most songs aren't even moderately challenging, even on heavy mode. The workout mode makes no sense to me; it will track your calories but you still have to play in game mode. This means that every 3 songs, you have to go through the whole loading process again. In DDR Max 2 the workout mode is different...you can play 400 songs if you want, without starting over. The nonstop mode is also frustrating as you can't customize it.
Summary: I am a longtime fan of the Dance Dance Revolution series and own virtually every game in the series, US or Japanese. And while I go back and play most of my older games regularly, I never play this one. Why? Because of one bug. Due to a programming glitch, the "Dance Play Settings" menu was omitted. As a result, it is impossible to disable the corner buttons on a dance mat without a gameshark or similar modification device.