Nevertheless, differences with IIDX are numerous: first of all, there are nine buttons to hit, and instead of having them clustered on a small area, they are round, big, colored and broad-spaced. The controller itself makes roughly 75cm / 30" wide, you therefore have to move your hands across this entire surface to validate the notes. This may be cakewalk on easiest levels, but as the difficulty increase, the effort required is quickly noticeable.
Second difference is in the interface. Unlike in IIDX where you could see a sober, cybertech universe, the pop'n music universe is richly colored, and is swarmed with "childlike" characters, as the recurrent Mimi and Nyami that appear on foreground and on every title screen. Even the notes follow this style: they are animated and have eyes!
One can believe by this presentation that pop'n music is a game for children... totally wrong! Difficulty is really there, but beginners can also enjoy the 5-button mode without too much hassle.
As far as the music goes, even if a great quantity of Japanese lyrics can be found, pop'n music also have its variety of genres. One will also notice that each version of pop'n contains a selection of TV show themes or anime songs. Fans of the genre haven't hesitated to test the famous "Zankoku na Tenshi no THESE" on 9 buttons...
Just like beatmania, success or failure is determined by the status of the gauge. If in the small red zone on the far right side, it's OK, otherwise you lose.
Last thing, don't say you're incompetent! There has to be songs for your levels, even on 5 keys. Just keep on progressing until you can reach 9 buttons as soon as possible. It's true that those who have tested beatmania IIDX before would have more or less ease with pop'n (such was the case with me), but mastering IIDX is by no means a requirement, definitely not!