So, I've installed beta 2 on fresh install of Windows XP with SP2, to see what it is like. So far I've noticed that this version supports fixed positioning in CSS, translucent PNGs and :hover on other elements other than just 'a', however that is where the good news ends as other than that I haven't found anything else that has been fixed. I notice for example that IE7 doesn't recognise the XHTML mime type, :before and :after pseudo classes and it also seems to have made very little progress on the acid2 test. It seems Microsoft have at least implemented the most useful features that were missing from IE6, however the current set of features I feel is where Opera and Mozilla were in 2003/2004 and they still have some way to catch up to the state of the art.
So will IE7 reverse the flow of users from IE6 to firefox? well that's the question everyone's asking. I actually don't think that it will for the following reasons.
The first reason for this is availability. IE7 will only be available for Windows XP SP2, so if 60% of Windows XP users have SP2 and 72% of users use Windows XP that means currently 43% of users can install IE7. For the remaining Windows XP users, the fact that they haven't upgraded to SP2 yet so long after it was released probably means for what ever reason they are not it great hurry to do so. The W3C browser stats show that in 2005 Windows XP share of the market grew from 61% to 72%, so if this rose to 80% by the end of 2006 and SP2 usage was at 80% also, this would still only be 64% of users. In comparison Firefox is available for at least of the platforms in uses as it covers Windows XP, Linux, MacOS X and older versions of windows such as NT, 98 and so on. Users of windows 2000, NT and 98 systems will realise that only way to get a modern browser is to upgrade to firefox as IE7 will never be available for their platform, unless they upgrade to Windows XP which will in most cases require a new PC to be bought. Even in cases that users have Windows XP SP2, IE can only updated by the system administrator which in a work environment is typically someone else, so this could take years before it is properly tested and deployed. In contrast firefox can be installed by a normal user and does not require admin privileges
Another reason is that IE7 is all or nothing upgrade, IE6 and IE7 can't easily co-exist and so if IE7 has some problem, the short term solution maybe to go back to IE6. Where as with Opera and Firefox multiple versions can exist with each other and of course with IE.
Yet another reason is the quality of IE7 it's self, the first release of IE7 is likely to buggy, compared to opera and firefox, due to the amount of new code it contains and the short time in which this latest version has been produced. And even is this turns out not to be true, there doesn't seem to be anything radically new in IE7 that would make an existing users of firefox and opera switch back, for instance the main new features seem to be the phishing filter and the tab expose feature, these features provided in firefox with the google toolbar and the Viamatic foXpose respectfully.
The final reason is site support. One reason that IE6 is still so popular is that it is supported by the largest number of sites of any current browser, firefox is close behind. However with the release of IE7 there is a good chance that it will support less sites than firefox does mostly due to browser detection scripts and behaviour changes Microsoft was forced to make to fix things.