The concept was cool. I enjoyed trying to determine which circle will hit first, and if two circles would hit at the same time, lining it up for the next color as well. The music (of the two songs I tried) was very calming and peaceful. Overall, this was very enjoyable.
Looking down to figure out the next color, only to need to look back up to figure out where the color is and where the next ring will hit was one step too many for me. Upon completing a row of the colors, the game would usually spawn me something impossible to prepare for.