Pros: Hearty construction takes years worth of beatings and continues to work like new.
Cons: None. Its for real. None!
The bottom line: Highly recommended from this graphic designer. It boils down to preference but this product is top of the line!
I am a graphic designer. My work demands that I have excellent input hardware that will take a beating and still function properly. A few years ago I was also a gamer on top of my regular graphic design routine. Needless to say, I spend a LOT of time at my computer(s) and demand quality from my input devices.

The Trackman Wheel by Logitech is without a doubt the greatest thing on my desk. So great, in fact, that I now own 3 of them. I invested in the first of the three about 6 years ago. It is the 'old school' styled trackball before they became the more sleek version which is what you see in the product photo.

My first trackball is still working today and its on my third computer. The only problem on this trackball is that the rubber on the wheel has basically worn out. A design flaw that seems to have been corrected in the newer version of the Trackman Wheel.

Software:
The Logitech Trackman Wheel comes with Logitech's specialty software but will work with virtually any device drivers and the newer ones plug in via USB so Windows basically installs the thing on its own.

The software allows you greater flexibility over your buttons. A word of caution to gamers though, I do recall experiencing difficulties with the software and key binding. What those problems were I really can't remember. I'm married now and prefer to read books than to play online games!

Build Quality:
All of my Trackman Wheels have fallen off the desk repeatedly, survived multiple moves, and stand up to a heck of a lot of use.

With age comes the only wear point in the hardware: the rubber feet. They do come off eventually but replacement is simple and I don't think they could really do anything better in this area.

Cleaning & Maintenance:
The newer style is way easier to clean than the older ones. Just pop the ball out with a pen and its a matter of thumbing off all the gunk. Super easy.

Cons?
None to speak of. That's all there is to it. 3 Trackman Wheels in my house used constantly for many years and they all still work absolutely perfectly. The rubber feet wearing off after several years of use can't really be something to call a con, it's what I call normal wear and tear.

New vs. Old:
The 2 newer style Trackman Wheels I have were purchased about 3 years apart. The older one feels IDENTICAL to the new one. This just goes to prove the quality isn't even degraded after years of use. The only difference from my older one to the newer one is the "Logitech" paint is still on the top and the feet are brand new.