I'm very pleased with the MX Master 4, the 4th mouse in the series I have owned. It operates smoothly and as the previous model have, it fits comfortably in my hand. What I'm most interested in see is how the finish material that my hand contacts "stands up" to long term use. Hopefully it is more robust than earlier models. I'm also interested to try out the enhanced mechanism to set and select program actions more efficiently.
Feels great, looks great, clicks great. Made of really quality materials too. The horizontal scroll wheel is fun to fidget with, functionality aside. My only gripe with it is the low polling rate, 125 Hz. I know this is better for battery life, but I'd at least like to change it so that I could use it for gaming if I really wanted to. Other than that, fantastic mouse.
I finally replaced my MX master with the MX Master 4 after the rechargeable battery gave out. I like almost everything about the Master 4, however I had to disable the new thumb button because it is so sensitive that I kept on pressing it by mistake. Unfortunate since on my MX Master I used that button as Ctrl + a (select all).
The mouse fits my hand well and the cover does not get sticky. The only issue I had was that the mouse was used by someone else before. As with the keyboard I purchased. The second one that was sent to me did not have as much wear as the first one so I kept it. It is a real hassle to return and reorder something with Logitech.
And not only would I for-sure favorite the debut single from MX Master Mouse on Spotify, it's also a damned good input device for my PC. It's comfortable, fits beautifully in my hand, and has a lot of features that I love (especially the MagSpeed scrolling). I still accidentally click the thumb-triggered "Action ring" when I don't mean to, but turning the sensitivity down has helped with that. I need to spend some time setting the action ring up and getting used to it. I'm sure it's great but I just haven't used it much. Anyhoo, in summary, I've been using MX Master mouses since v2 and I love them. I wouldn't call an upgrade from v3 to v4 a necessity, but I bought one for home and one for work so I guess you could say they're my favorite. A++++++ 10/10 Would recommend.