I have tried IE9, and to say it is a massive improvement over IE8 is a serious understatement. Mind you, IE8 wasn't as bad as IE7, 6, or 5 (and 5.5)... but IE9 blows them all out of the water, even in its beta state. Hated the cluttered UI of IE7 and 8? Rejoice - it's gone. In its place is a much more compact UI that takes up a lot less space, and is more functional at the same time. Tabs are located to the right of the address bar, a place I've never seen tabs before in a browser. Like previous versions of IE, the menu bar is hidden by default, but can easily be brought back if it is needed. Microsoft has also posted a bunch of interesting demos of new functionality in IE9, and their demo page got a big update with today's IE9 beta release. My favorite is Psychedelic Browsing. Note that Firefox, Safari, Opera, and Chrome don't handle this demo very well - at least the stable versions of those browsers. I tried the September 14th nightly build of Safari (called WebKit) with the demo, and had near-identical results to stable Safari. I have NOT tried Chrome 7 beta, though, and I can't seem to find the Opera beta on Opera's site. Note that the beta, like the Platform Previews before it, requires Windows Vista (SP2, with a few post-SP2 updates also installed) or Windows 7 (a few updates are required here too - these will be installed during the IE9 install process).