g7 is a nice mouse thought the battery drains quite fast. I would love logitech include 2 side buttons. Their new mouse looks really awesome and I tried the scroll wheel at local store it rocks I think.
I hear that the Logitec laser mice have had problems with shiner surfaces/mouse pads such as the icemats. However, there was a recent firmware update that many people have reported as fixing these issues.
Personally, I've got a G5, the G7 wired counter part. Where the G7 has the battery, the G5 has adjustable weights, which is pretty nice as you can change how the mouse feels. It's also got a clothy/nylon cord instead of the normal rubber cords and it reduces a lot of friction.