Just upgraded from my trusty g602 to the g604. Buttons aren't nearly as clicky and tactile as the g602, but the damn scroll wheel is phenomenal, I can't get enough of it.
G602 Vs. G604 Lightspeed
Video Review: Logitech G602 Wireless Gaming Mouse — GameTyrant
Logitech G604 Review | VG247
Amazon.com: Logitech G602 Lag-Free Wireless Gaming Mouse – 11 Programmable Buttons, Upto 2500 DPI : Video Games