Pros:Requires less desk space than a mouse, more comfortable to use.
Cons:Requires cleaning at least once a week to maintain smoothness.
The Bottom Line: A great alternative to a mouse, give it a try, you'll probably like it better than a mouse.
For over 10 years I have been using Wacom pen tablets on my PC even though I do no graphic design whatsoever because it's simply the most comfortable and accurate pointing device.
But I also use my PC as a home theater PC on my large HD front projection screen and the tablet isn't wireless, I used to use the wireless mouse that came with my keyboard but using a mouse on a couch isn't the best option. I saw this trackball at the store the other day and thought it would be a good option so I read about trackballs before buying it and what I read on them really recommended getting one.
I got used to it quite fast, after experimenting with different cursor speeds until I found the speed I preferred. It's very easy to use and in fact when I tried my mouse again to compare it felt awkward to use and I immediately went back to the trackball. It has a scroll wheel like every mouse has and back/forward buttons.
A trackball offers many benefits such as requiring less desk space since you don't move it like a mouse, and is more comfortable and easier to use than a mouse.
This trackball is a wireless model that uses the Logitech Unify mini USB receiver that barely sticks out half an inch from your PC or laptop and has much better range than the older bigger receivers (it has never lost the signal while my older Logitech mouse/keyboard need to be at just the right angle to work if they're more than a few feet away).
I found the ball and bearings need cleaning every several days, you can feel the ball get less and less smooth, but just pop it out with the eject hole underneath and wipe it clean as well as wipe the 3 mini ball bearings inside and it's like new again for a few more days, it takes seconds to clean so it isn't a big problem.
The battery lasts up to 18 months according to Logitech, I always use rechargeables anyway as it makes no sense whatsoever to buy non rechargeable batteries, plus rechargeable batteries last about twice the lenght of alkalines per charge so you replace them far less often, but on low drain devices like this it's best to use the new Precharged/Low Self Discharge batteries.
The trackball turns itself off after a few minutes of inactivity, so there's no need to use the physical on/off switch, it's meant to turn it permanently off for storage to avoid accidentally doing stuff on your PC if it's moving around in a bag. When it turns itself off automatically, it will turn back on within a second of you touching it.