I owned the Logitech MX518 mouse since its release. I needed another mouse and bought this one. After so many years with the previous version I noticed a lot of subtle things about this mouse that I didn't like. The G500s that I bought had a defective scroll wheel. It wobbled, and would roll backward, so I could not use smooth scroll to any capacity. The mouse programming buttons were limited, and slow at maximum settings. Working in a high resolution space I would say this is the very bottom of gaming mice. The feel is nice and more responsive than the MX518 but not smooth while doing artwork.
I've reverted back to my Steelseries sensei mouse, because of it's extremely high DPI (double the G500s), smooth feel for artwork, and multitude of button configurations. The G500s feels better in the hand, but is not a strong contender to the likes of Steelseries, and Roccat. Razor mice fall into the category of paperweights. Since their button switches break quickly.
I also bought this mouse as a replacement for a previous Logitech mouse. Coming from the Logitech G5, i had to adjust to the new feel and shape of the mouse. The scrollwheel is loose for me as well, but with some adjusting (like a month?) i now confidently and accurately scroll. After getting use to this mouse, i'm really happy i got this one. The buttons feel great, the weights are a real nice touch and the extra thumb buttons are a welcome addition to my DotA 2 keybinds ;-)
I just felt like i had to add some positive to this review, seeing as my perspective and experiences were not represented on this page .