TL;DR: The main mouse buttons are stupidly contoured! Like, really stupid!
First the good. Form factor is really spot on. I love how this mouse feels in my hand and the angle is very comfortable. It's programmable which is great. And has a lot of button assignment flexibility. Picking it up from the mouse pad is kinda funny, but that's about it.
I read some complain about its inaccuracy, and it does seem that way, but I can't tell yet if that's inherent or if I just need to get used to it.
But now for the bad. The bad is honestly, just one thing, but it's such a big thing that it throws this entire mouse down!
Although the mouse is nicely oriented, the design of the actual buttons has them curving down toward the base! And no one's fingers curve like that! So what ended up happening is my fingers go across the mouse buttons diagonally! Try rotating a regular flat mouse 30-45 degrees away from your keyboard on the mouse pad (still flat, not lifting it) and then hold with you hand at the original angle. That's how awkward this feels. And I can't understand how they could do this!
If this was their first vertical mouse design, I could have maybe understood this design flaw a little. But they have a right-handed vertical mouse (the Perixx PERIMICE-608) with far more naturally oriented buttons. If they had just flipped that mouse to make a left-handed version I would have probably been much happier.
So why the hell did they decide on this redesign for a left-handed mouse? Sure it looks sexy, but it is useless if it doesn't work comfortably!
Left handers have found a few different ways to deal with a regular flat right-handed mouse. I hear some left handers shift their index fingers back and forth to use both buttons, and many reprogram the buttons switching left and right. But I work in an environment where I had to use other machines for a few moments at a time and where other users had to use my computer from time to time, so reprogramming the buttons wasn't always practical for me. I instead simply adapted to using the mouse with my middle finger for normal clicking and my index for right clicking. And it has become perfectly natural for me. But this "left-handed" mouse makes that VERY uncomfortable! The way the buttons fall, I end up using my damn inaccurate ring-finger to click, my middle finger for the scroll wheel (which is also at an odd angle for my finger) and my index finger struggling to right-click.
This mouse looks really nice, and feels good in my hand; for that it got two stars. But it completely fails in functionality.
I honestly want to return it, but it's too difficult from where I live, and I would never give this any left-hander I know. It's too damn stupid.
So, I'll just have to try another brand. And choose wiser next time!