Did you install it through Windows Up-dates as I did today as it has now been officially launched by Microsoft ?
I have not had enough time to explore all the features fully yet, but have posted a thread under 'Internet' hoping VHG, Rojash or Chuckfickens will respond.
Sometime ago I updated from IE7 to the beta version of IE8. Like you I hated it and tried to revert back but for some reason IE would not accept a backward installation. In the end I had to do a recovery which involved a lot of updating. Now I occasionally save the complete image of my hard drive so enabling q quick return to a good system.
This can be done on a separate partition or an external drive.