Once upon a time I got sick of the gunk build up on all the mice and trackballs I had used, it got to the point where they would bump and jump on the mouse pads.  I was intrigued when I saw the technology used in the  Trackman line, detecting position using the tiny dots on the ball.  Now  having used the FX Trackman at home and at work for over 3 years, I find  that it is the still the best input device of its kind, including the new  MSFT optical mice. Once one gets used to the button placement and develops  the dexterity to utilise the trackball, constantly smooth and consistent  movement will reward them. With no moving parts for the tracking assembly  the user only rarely [once a year?] has to pop the ball out and clean the  sensors. This trackball does very well in digital art work with Photoshop  and is especially excellent when used to play classic trackball arcade  games through Mame32 emulation, Missile Command, Tempest, Centipede,  Arkanoid, etc. The tertiary buttons are recognized and used as scroll wheel  counterparts in Win2k; it's a nice fluff feature. My only wish would be  that Logitech eventually upgrade them to use USB so I can plug them into my  MSFT keyboards. Otherwise, highly recommended.