The posture of the hand and the arm is more comfortable than a normal mouse per se, because the arm or wrist are not so twisted. However, the palm rests on the table and needs to be raised with greater movements sometimes.
In the time I've used the mouse, I could not win the necessary navigation safety, which I'm used to from normal mice. This is certainly due to the lack of habituation, but mainly on the concept and its implementation. By more or less laterally guided click, a corresponding lateral movement torque is transferred to the comparatively slight mouse. This has at least led me to the fact that the mouse cursor is often slipped back when I click and I had to repeat the action (or, was even worse, triggered an unintentional action). The targeted clicking or exact marking of small objects was thus quite tiring and annoying. I can not imagine that this problem disappears by exercise alone me. Whether other vertical mice (perhaps due to a higher weight) does not have the problem, I can not judge.
I would probably still mouse given a chance, despite the difficulties mentioned earlier, if not for a short time a really unnerving problem would have occurred with the mouse wheel. If I wanted to scroll down a bit, the screen contents are scrolled only upwards and then downwards. This "back-and-forth" occurred very often and was especially in reading screen contents exhausting. It also meant that you had to run a lot more scrolling movements as necessary, which also can not be called "ergonomic". As other users have apparently observed the same phenomenon, which seems to be rather a fundamental problem.
Conclusion: Without the Mausradproblem (which probably does not always occur), the mouse might actually for some a good alternative to regular mouse. Mainly due to the above-described, in my view immanten and not by habit eliminatable Navigation drawbacks I can not recommend the mouse.
