The Bottom Line: I would recommend this as a simple trackball that works well and is easy to use.
This mouse wont win any awards for having the most buttons or features, but what it lacks in extras it makes up for having the basics down pat. I picked up the Kengsington Orbit Trackball with Scroll Ring as a replacement to my logitech trackball that didn't have a scroll wheel. The scroll ring works perfectly and I'm happy I made the switch. I use the trackball for gaming & surfing, I have no complaints with the accuracy is for both Team Fortress II & World of Warcraft. Ergonomically (with the included wrist wrest) it's comfortable to use for hours on end and everything is placed perfectly to be easily usable for both left and right hands. The scroll ring is recessed enough that standard clicking and movement wont rotate the ring, however its high enough so that if your trying to use the ring its very easy to access. The only downside for the mouse that I see is the wrist rest comes off pretty easily if its not on a stable surface. I have it sitting on the arm of a lazy boy so it will come off a couple of times a night, I havent figured out a good way to glue the rest in place.