Yesterday at All Things D, Microsoft announced Windows 8 (codename of course) details, and a first glimpse on video
My initial reactions to this, as a consumer and as a development manager of an app that at this time is completely windows desktop .NET based:
HTML5/JS Apps
First reaction? Why not just use a browser? and How are they going to interact with the OS? What level’s of rights will they have to read/write file system, etc, etc. Also, what happens to Silverlight? C++/Winforms apps? Yeah they show old apps running “behind” the new UI, but what is MIcrosoft’s stance on development of these other technologies? WPF? They have told devs to build using these tech’s for desktop for years, now, lets go HTML5/JS? WTF? Will apps run in browser too? On a mac? iOS?
Tiles
First reaction? Looks like an exploded Windows Phone UI, WP7. Which at first blush looks cool but I have found usability to be painful. Seems to be more of a shell UI on top of Windows 7 (or whatever). They should call it Windows Blinds 
In General
I think that this will be a good refresh for the OS, but it might take a few iterations for this new UI to be used heavily. My take? Users will get the OS installed and (hopefully there will be an option to) turn off the new UI and go back to what they have used for years. Slowly but surely the new UI will take hold with some cool apps and more and more people will use that and get used to it, abstracted away from the core OS explorer, etc.
Looking forward to trying it out in beta, and when it goes live. I will give MSFT this, they keep things changing so devs have to keep learning! Oh yeah, and PDC is no longer, it is now BUILD – http://www.buildwindows.com/
Steve Novoselac's Blog 