Thank God. 0.8 was really getting under my skin. Better than IE, but only barely. I've had a few big crashes on Windows, but my biggest beef is the layout and CSS compliance issues. I'm stress-testing 0.9 now to see how it holds up. Of course, layout problems are due to bugs in Gecko, not Firefox (Mozilla gives me the same troubles).
I've still noticed the "Sticky Alt Key" bug and auto text-select (sticky mouse button) bugs are still intact in 0.9. Bugger.
Plusses are fixed (and faster) mouse-scolling, a better extension manager, a smaller download, better auto-complete for forms and the ability to clear auto-complete on the spot, and supposedly, fewer bugs.
Minuses are the two default icon sizes (a choice between "too small" or "microscopic"), a poor style switcher, a simplistic download manager that takes up waaaaay too much screen space, and the fact that the extension API has changed, meaning all (most?) of your extensions will have to be updated before you can use them again.
Plus any non-IE browser I've used always displays annopying clipping behaviour when playing said files
Flash is notorious for mass CPU consumption. Though, that sounds like a driver issue.
