Quite good
Great vertical mouse.
You have to get the hang of it, and I have to admit that it is less accurate than a regular mouse. So don't think that "playing" with it will be easy or even that you will be competitive.
That said, it's not in the claims of the object so no worries.
Beware of the micro signal loss between the PC (dongle) and the mouse. Too much clutter between the two can impede the flow.