RC1 is feature-complete and largely bug-free. It appears nearly ready for widespread release, so don't be surprised if the final version arrives relatively soon.
In this review, I'll look at the changes made between the Beta 2 and RC1 releases of IE8. (Note that IE8 RC1 is available for XP and Windows Vista, but not yet for Windows 7 . The version of IE8 in Windows 7 is later than Beta 2, but earlier than RC1.)
Changes in Compatibility
You most likely won't notice one of the most important changes made with RC1: How IE8 handles Web sites designed for IE7 that cause compatibility problems with IE8. Previous to RC1, IE8 introduced its Compatibility View, which tricks a site into believing that you're running IE7. When you run into any compatibility issues on a site, you click the small icon of a broken page at the right of the Address Bar, and you can then view the site properly, as if you were using IE7. IE8 remembers that it needs to use Compatibility View on pages for which you've used the view before, so you won't have to click the icon each time you visit.
RC1 improves Compatibility View by automating it to a certain extent. Microsoft Corp. apparently found that a fair number of popular sites coded for IE7 were causing some compatibility problems with IE8. So it created a list of those sites and automatically feeds that list to IE8. Now, whenever you browse to any site on the list, IE8 automatically shifts to Compatibility View, without requiring you to take any action.
You can opt out of the list if you want. Choose Tools-->Compatibility View Settings, and uncheck the box next to the choice that reads Include updated Web site lists from Microsoft . To opt back in, simply check the box. The screen also lets you add sites to your own personal list as well. In addition, Microsoft says it will update the list every several months.
In practice, I found that this new feature worked well. In the beta, I had experienced a slight compatibility problem with my personal iGoogle page --- the Google Calendar applet didn't display properly on the page, although the calendar itself worked fine when I clicked through to it. When I visited my iGoogle page in IE8 RC1, the calendar displayed without a problem. In looking at the Address Bar, I noticed that the Compatibility View button wasn't being displayed, which means that I was viewing it in Compatibility View. I hadn't added iGoogle to a list, so it clearly was one that Microsoft included in its list of sites.
I was unable to authoritatively confirm either assertion, although my pages did load quite swiftly.
Tweaks to the Address Bar
IE8 sports an address bar, similar to those in Firefox and Chrome , that does more than just let you type in a URL. In Beta 2, as you typed text, it displayed results from your history, favorites and RSS feeds, and organized them all by category.
Microsoft says that in RC1, it made changes to how the address bar behaves, based on telemetry information it received by examining anonymous user behavior data from Beta 2. People tended to click through to sites primarily from their history list, secondarily from their favorites and very rarely from their RSS feeds.
As a result, the top of the Address Bar list now displays matching sites from your history and then from your favorites. By default, no matching sites from RSS feeds display, and even when you do choose to display them, the number of matching sites from RSS feeds is fewer than those displayed for history and favorites.
To tell IE8 to display RSS feeds as you type, you select Tools-->Internet Options-->Content, then click the Settings button next to AutoComplete.
You then get the AutoComplete Settings window. To tell IE8 to display results from RSS feeds as you type, you're supposed to click the box next to Feeds, then click OK. But that selection was grayed out in my version of RC1, and I was unable to tell the browser to display the RSS feeds.