Good idea and execution with catchy, fitting background music and nice, simple graphics. I also liked the details, like the "one frame too late" feedback, the generous control possibilities - both the key controls and when you want to start - or the way the levels advance.
However, it was really, really annoying that after a game you'd have a fairly long losing or winning screen, and playing again meant to have to switch to your mouse, just to click "play". There was no way of retrying by just using the keyboard. In such a fast paced game these are killers - in the bad sense.