I just installed Internet Explorer 8. Right after the install, I was taken to the Welcome to Internet Explorer 8 page which invited me to try the Accelerators feature. The first thing I did was to select the "One Microsoft Way, Redmond, WA 98052-7329" text on the welcome page, but that didn't seem to go too well - they seem to have a problem tracking my mouse cursor.
I got the Accelerators working with another page where I selected a bit of text on a page and got Internet Explorer 8 Accelerator to perform a Google Search for the selected text. The Translate Accelerator is pretty neat as it enables you to view the translated version of text in a WebSnap-like interface:
The Suggested Sites feature took a while to get started, but seems to be a great feature. I'm guessing Microsoft may be using it to find websites and gather statistics to add to the Windows Live search.
My overall experience with Internet Explorer 8 is pretty much the same as Internet Explorer 7 - the browser has all sorts of bells and whistles and feels really cool, but feels very sluggish even on Windows XP. Opening a new tab alone takes about two seconds while Firefox, my default browser, does it instantaneously. Web slices is a new feature that will send developers off to writing updates for their websites. The compatibility mode comes in pretty handy for older web apps that are IE-specific. It may take an update or two to get minor issues sorted out, but it is a welcome addition for web developers complaining about standard-compliance.