Neowin.net has a good review of Internet Explorer 7 beta1. The article goes into detail about the pros, the cons, and the bass-ackward interface changes.
“Microsoft is playing the catch-up game with IE7. Nearly every feature included with this build has already been successfully implemented in most alternative browsers. Crucially, the interface is still not up to par with Firefox/Opera; can we honestly back a new version of IE when there are alternative products on the market offering so much more?”