Pros: Comfortable, adjustable weight, and many buttons, logically laid out.
Cons: None! (Wireless would be a bonus, but not complaining.)
Logitech is the brand I've kind of gravitated towards. The products they put out are phenomenal, the customer service can't be beat (seriously I've probably had 10 RMAs over my lifetime with about 8 different products, and never had a problem), and the Setpoint software has locked me in. Being able to have your buttons do different things depending on the program has become so necessary that I'll never consider another brand.
I've owned the MX Revolution, Performance MX, VX Nano, G9, G9x, G700, and G500. When I was shopping for this mouse, (I had a problem with my G9x where the weight tray wouldn't stay in) I purchased the G700 first. I hated it. The G500, while uglier, fit my hands much better. It's such a comfy mouse, and I now own two (one for the office, one for home) that I'll probably be very reluctant to switch from it. It's like the Cadillac of mice. Yeah, the Cadillac of mice.