I've been using this a majority of the time since January 2021, and this is the most comfortable and best-designed vertical mouse I've used. I have four of these, and two of them have broken in some way. The first lasted about a year and a half - the scroll wheel sensor acts up, never sending a complete scroll event (a reverse is often paired), and the second's (lasting a little less than a year) middle click button ocassionally doesn't fire an event. I imagine at some point I will begin to repair these with old donor parts, or customize them in some way, but I haven't gotten around to that yet.
A wired mouse is a necessity for me, as any wireless mouse I've tried has a connection delay after a period of inactivity (albeit small), and I don't want to worry about charging/a battery. I'm usually able to route the cord in a way that doesn't prevent fluid movement.
The sensor is great, and is capable of relatively small movements/adjustments. There are some other products whose sensor has trouble with certain surfaces or small movements. The optical sensor faces and shines to the right when lifted.
The back & forward buttons are in a decent location to be convenient while prevent from being triggered accidentally, and the DPI button is far enough away that I only ocassionally trigger it when I'm grabbing my mouse after sitting down (I seem to hit this more than the back/forward). Thankfully there are only two modes, so switching between them is noticable & easy to do. Other mice have upwards of four different modes, and it can be difficult to determine which is which.
The surface finish is slightly velvet-y, and feels good, but will show hand oils - after a week or so of use, I think it becomes noticable. This doesn't bother me, but in an office environment, this may be something you're concerned about. It seems to be able to take standard cleaners well, but I mostly just use dish soap & water.
There is space on the right side of the right click button that allows your ring finger to rest & grip - this is the main way I move the mouse (along with my thumb), with my pinky resting/gliding on the surface, or paired with my ring finger. The right edge of my palm is what contacts the surface of my desk, and if your hand is positioned above your elbow, this area may become sore. After moving my work surface lower, with my elbow straightened & raised, it prevented this for me.
There is a red light bar on the left side of the mouse that is on whenever the mouse has power.