The validation was really fast and the installation took only 3-4 minutes. Unfortunately, you have to restart your computer before using IE7.
This is the welcome page you will see in IE 7: you can set up a phishing filter, choose region and language.
Then you can visit two nice pages: Developer Checklist and IT Pro Checklist, that let you know about different changes in IE 7 rendering engine like: alpha transparent PNGs are supportes, some CSS hacks may break your pages. You can also download a developer-targeted toolbar that lets you explore the DOM, validate pages and outline different tags.
The first bug I noticed: you can't use Compose tab in Blogger. Other issues: if you have Google Toolbar 4 and click New Tab, the toolbar disappears. The phishing filter doesn't seem to work.
There is no "Open in new tab" option when you right-click a link, so the tabs won't be used too much. The new tab button is counter-intuitive. Compare in the screenshot below the way "New tab" was implemented in IE (first) and Opera (the second).
All in all, the new version of IE has some strong points: the new RSS reader, the print preview, the new zoom and the clean design. It crashed only once in several hours of use (when trying to print preview a page) and, unfortunately, didn't show any error message or recovery features (like session saving).
(Yahoo Mail login in IE 7)