Coordinating the D-Pad dancing and the touch screen tapping was quite easy to do in the first level I tried, so much so that I asked for a tougher level right away. As if to show me who was the boss, I got one of the harder songs in the game, at which time I was promptly whooped. Hitting the correct buttons on the D-Pad to the beat of the music was easy enough, but I also had to make sure the slimes were being cleared. Coordinating this was really hard, especially since the tapping and circling wasn't fixed to any particular beat of the music. I could clear the screen any time I wanted, which made juggling the rhythm of the D-Pad and the disarray of the touch screen very intimidating.
I cried Ouendan on that stage and went to something that was medium in difficulty. Though it was hard to hear the music (despite a pair of big headphones and a quieter E3 show floor), I think that the music and the touch screen patterns may line up in a certain way, but that way must be discovered by the player to make the best run at a high score. Looking back, I don't know if such a thing was possible in the nightmarishly hard song that I tried out, but if Ontamarama is indeed designed in such a way, it may knock the socks off of Ouendan in terms of difficulty. Otherwise, the game is an uncoordinated mess.
I'm definitely interested in Ontamarama, though I would have liked more time with it to be sure about some details. Despite that, there's always room in my game library for a new music game, and based on what I've played so far, I wouldn't mind including Ontamarama in it.