I have used a Logitech Trackball mouse for years and I love it but when I'm doing a lot of mouse work (highlighting text to cut/paste it and move it around on documents) I start to feel the stress in my elbow and forearm from having my hand rolled over onto the trackball for so long. When using this joystick-type mouse, my hand and wrist is rotated 90 degrees clockwise to how it is when using the trackball and it seems to completely relieve that stress on my elbow and in my forearm. Maybe with extended use it might stress other areas or cause different stress in my elbow and forearm where I would need to periodically change back and forth between the two but for now it's a welcome relief. It didn't take very long for me to get used to and it's simple to use. The button on the top of the vertical column is both a left and right click button and there's a separate button on the vertical column for scrolling.