It doesn't seem that ergonomical to me. Although it looks like it might be good for the "hand posture", i wouldn't be able to be keeping the right posture all the time.
Also, it looks like it's not to handy to just grab, do a small movement and release again. I also don't exacly love it's size, way too big and high for my tastes.
With all that i mean... Nobody will ever make a mouse better than the one i have right now: