Coming from Logitech's M570 trackball and trackman wheel, some features puzzled me.
First, the ball is loose and does not lock in place. It easily moves or falls off with a tilt or flip.
While it is more practical for regular cleaning, there is a high risk of it falling and breaking.
Regarding ergonomics, I prefer the ball on the thumb to handle mouse movement, while the rest functions like a regular mouse, with a middle scroll wheel that is missing in this one, instead of the ball on the index and middle fingers.
After prolonged use, it becomes tiring and requires continuous finger pressure.

On the positive side, the design is visually appealing, the build quality is good, and of course, it is suitable for left-handed users!
There is a TrackballWorks application that you can download from Kensington for button customization.