I have heard about this for the first time looking at an ad in the last months OPM (awesome ad, btw) They also had a short preview. Apparently, the game is made by the same Namco team that made Donkey Konga, and it plays in a very, very simillar way. Seeing that I really liked what little I played of DK, it instaly piqued my interest.
They also said in the movie "Lost in Translation", one of the guys in the arcades plays this game (and I actually remember seeing it, except I had no idea that was it when I was watching the movie)
Here's how it plays:
You have one drum, that has four areas/sensors below it's top surface. Outer left, outer right, inner left and inner right. You use sticks to drum. There are four different simbols that slide across the screen. Small red circle means slapping once with one stick on either left or right inner area. Big red circle means slapping with both sticks once at both left and right inner area. Same principle for small/big blue cirles except that you slap the outer area(s). Extended yellow line means drumming continously as long as the line slides through.
Btw, one of the songs featured in the game is "Katamari on the Rocks" which pretty much cements the purchase for me.