While the focus of IE 7 was on security and the incorporation of a tabbed interface, version 8's main features centre on stability and usability.
In terms of stability, IE 8's new automatic crash recovery feature is designed to solve one major problem that most IE users know all too well. Today, when an IE window or tab freezes or crashes, other browsers instances or tabs will likely become inoperable as well.
Automatic crash recovery does a better job of isolating instances of the IE browser - or separate tabs within the same browser - so that one stalled browser or tab can be terminated without affecting any other. More>>