The G9's two main buttons are fine (and also hard to screw up). But the two thumb-side buttons, the scroll wheel, and even the two buttons dedicated to scrolling through the various sensitivity settings all just feel wrong. The thumb and dpi buttons are narrow little strips that require too much conscious thumb or finger positioning to press them accurately. Our impression isn't limited to that of one reviewer's hand; multiple members of CNET's editorial staff had the same complaints.
And while we welcome the addition of the free-spinning scroll wheel to Logitech's gaming mice (as on the Logitech MX Revolution), it's not as useful as those we've seen elsewhere because you can't change it from free-spinning to the more typical stepped movement on the fly. We suspect the reason is that the original design required you to push down on the scroll wheel to change between spin modes, but on a gaming mouse, pushing down on the scroll wheel typically gives you a third button function. On the G9, the scroll wheel retains its third-button capability, and you have to press a separate button on the underside of the mouse to switch between free and stepped scrolling. That effectively eliminates changing modes on the fly. True, the free-spinning mode is most effective for navigating long documents, and most game applications of a scroll wheel don't need that much freedom, but we think Logitech could have found a more elegant solution.
As with most gaming mice, the G9 has a programmable laser sensor, but its 3,200dpi upper limit is the highest we've heard of. We find that 2,000dpi is more than adequate for scrolling quickly across a high-resolution monitor, so we have a feeling we're crossing into overkill territory with 3,200dpi. You can use Logitech's software to customize both the sensitivity settings as well as the polling rate (the accuracy of the laser readings, at the cost of system performance), which now goes to 1,000MHz. Logitech also includes buttons for toggling between five different sensitivity presets (with a color-customizable indicator LED on the mouse itself), although we're also happy to report that you can map the dpi buttons to other key commands in the software. Those buttons might not be the easiest to use, but at least it's an option, and one not offered by the Microsoft Sidewinder.