Flash-fan or no (I'm not), there's no denying Adobe has put an insane amount of work into this release. From experience I know that the work on improving performance across the board can be seen with the naked eye: processor load dropped significantly after installing the 10.1 betas and release candidates, so I'm hoping the same will apply to the final release.
The improvements in performance go hand-in-hand with work done to lessen the stress on battery life for laptops. For instance, when Flash content is running in the background on a non-visible browser tab, Flash 10.1 can reduce its load on the processor for that specific content. Memory usage has decreased across the board, and when memory does run low, Flash Player will automatically shut itself down to make way for other tasks.
Flash 10.1 also brings hardware accelerated playback of H264 content to Windows XP, Vista, and 7. Sadly, this feature, which decreases Flash' processor load significantly, is not yet available on the Linux version, and the Mac OS X version won't have it until some time after this release. This is the case because Apple didn't expose the proper APIs until very recently. You can download the Gala test release which enables H264 hardware acceleration on Mac OS X.
Speaking of the Mac, Flash 10.1 brings a lot of Mac-specific improvements. Flash Player 10.1. is written entirely in Cocoa, and uses a Cocoa user interface for dialogs, Core Audio for sound, Core Graphics for printing, and Core Foundation for bundle-style text. Core Animation is used to speed up rendering performance, and on Mac OS X 10.6, hardware accelerated Core Animation is used.
There's a whole lot more going on here, including multitouch support, so this is just a selection. You can download Flash 10.1 from the usual location.