Just got it in the mail today, most unexpectedly.
I might as well unbox it and give it a chance while digging up any reviews floating around for the 2012 variant, since it's clearly out now.
First impressions: This mouse feels really nice to hold, maybe even nicer than the MX500 variants Logitech's been using for years. The driver interface also seems more straightforward, though it did require a reboot to install. Every button has a really nice click to it, even the thumb buttons.
Razer's also one-upped Logitech in a few other areas, such as allowing buttons to switch to a certain DPI for as long as they're held and going back when they're released, or allowing the mouse wheel to change 100 DPI increments for as long as the button's held. It also lets me rebind the mouse wheel scrolling directions for those games that don't support it (and I've encountered a few, surprisingly enough).
However, if I could toggle the mouse wheel DPI switch and let it change in increments greater than 100, that function would be a lot more usable. The Razer control panel also takes a lot longer to start up than Logitech's SetPoint II.