I've been using Logitech's Track Ball since before it went "wireless"; well over 10 years. I went wireless with the Model M570 several years ago. I have one for each of my five PCs but needed another for my Chromebook.

Can't be used as a regular mouse to move on a mouse pad. Only the scroll wheel can be used for that. That is the biggest drawback. Wouldn't recommend to anybody.

I purchased this simply because I wanted to try a trackball. It is now my most-used input device. It is very comfortable, moreso than most traditional mice. Part of this is due to the shape of the trackball, but the fact that the hand stays stationary is also a factor.

- Excellent battery life (2 months and counting!; - Very comfortable

- Limited performance compared to some "regular" mice; - Poor scroll wheel

Overall I am happy with the initial performance of the mouse, but it has given me a few problems the longer I have had it. Advantages: Initially the trackball is smooth and works perfectly. It helped me a lot with the wrist pain that I had from my old mouse.

For the past 12+ years, I have been using the corded Optical Trackball that Microsoft made and then discontinued. Seems like everything they make that has a proven track record gets discontinued with them (Win98, XP, Win7, etc)! I couldn't find anything that had the same configuration until now!

Fundamentally, this a good product. It is conceptually sound, however it does throw a curve every now and then. It will seem to be working as expected, and then all of a sudden, it isn't. Then it usually comes back if you can be patient.

Sure anyone new to it always wonders what it is or how to use it, but I absolutely love it! once you get used to it having your hand stationary, and having it be so reliable is fantastic. downside. you have to clean the guides occasionally as they get dirty.

I have been using trackballs for over 30 years. I have 2 of these, one for home one for work. The one at home I've had for 9 years and just recently required replacing. I was pleased to be able to get the same model again.

This is an excellent product. It is very useful if you are using a laptop whilst sat on a settee because you can use it on the arm of the settee when a standard mouse needs a flat area to work properly. It works well with games or just navigating around. I would recommend to everyone.

I would buy again. Actually I'll probably buy one now just so I have one if they change the design. Old dog, new tricks and all that.

I've been using this for about a year now and I'm very happy with it; Take the time to adjust the up direction in the software, it's way easier than learning "up"; I've dropped this thing so many times I've lost count; It still works.

I wish it had a few more buttons; I got the extra two programmed to "hide" and "unhide all" in Sketchup; Great for long trips, I even do CAD work in the truck when we travel; If it had more buttons and a lower price I'd give it a fifth star