1. Windows Phone 7's theme and UI - this is a really big change. Take a look:
2. Ribbon User Interface in Explorer - not really a biggy, always expected the next versions of Microsoft products to have the ribbon user interface.
3. Cloud Integration - using Windows Live Mesh to move files between my computers already, but no SkyDrive yet. Of course it will be cool to get better integration but I always thought the Cloud to be more, much more, than the Mesh and SkyDrive. :-)
4. Windows Live Integration - more? Using my Windows Live account to log into my computer, how will that work in a domain? Intriguing.
5. Built-In PDF Reader - this will be done using Microsoft Modern Reader. Good, but where is XPS?
6. ISO Mounting - been using a third-party solution for this for a long, long time. It will be great to get an integrated solution.
7. File Download Verification - more malware security
8. Aero Auto-Colorizaton - no need.
Then Howard Wen mention the rumored features of Windows Store, ARM Processor Support, Factory Reset, History Vault, Instant-On, IE 10, Multi-Touch and Really Fast Install. You should take a look at these, this is great compilation.