While this design requires you to keep track of the cable (or find a full-USB-to-mini-USB cable somewhere), we much prefer it to the sort of clunky recharging stations that Logitech has used in the past and that Microsoft still uses in a trimmed-down form. Such stations prevent you from working while your mouse recharges.
Otherwise, Logitech has only implemented a few tweaks to its successful MX mouse formula in the Performance Mouse MX. You still get Logitech's innovative scroll wheel, which lets you switch between ratcheted and free-spinning scrolling (the latter is excellent for navigating long documents or Web pages). A new button on the thumb side also lets you toggle the scroll wheel to act as a zoom control. You can reassign any of the buttons via Logitech's intuitive SetPoint software, including mapping one of them to switch between two custom dpi settings.
Logitech has also tweaked the form of the Performance Mouse MX. It takes the basic design of the MX Revolution from 2006, but has a deeper channel for your thumb and a narrower heel. The result gives your thumb a snug grip on the mouse, which makes a small but noticeable improvement to fine motion control.
The Logitech Performance Mouse MX is expensive, but worth the money. Even if you don't need to exploit the versatile Darkfield sensor, it offers enough other useful features to justify the investment.
Additional editing by Charles Kloet