It's available for anyone who want's to try it out from here: http://windows.microsoft.com/en-us/windows/preview
Is Windows 10 really a whole new OS version? No, I don't think so. I'm pretty sure it was what they were going to release as Windows 8.2 (Windows 8, Update 2) but decided to go with the approach that worked well for the change from Vista to Windows 7. Try to cut the connection between the bad press of Windows 8 and learn from previous mistakes. Again.
As I play with it some more, I'll add to the following list with anything that grabs my attention.
- Being able to have Metro/NewUI apps as windowed instead of full screen/snapped is really nice.
- Considering it was an in-place upgrade, it is noticeably faster. Whatever extra special caching/pre-loading is going on is working really well.
- Start Menu - I guess it will be the big thing that get people over the whole "windows 8 is crap" thing, and it's just something I'll have to get used to. I actually preferred the ability to see a lot more in the Full screen start menu, despite the "jarring" transition when changing from the desktop. I think it will be good for a lot of people, and I will get used to it. It does have some nice additions though. (Just found there is an option to use the old Start Screen instead)