I had a chance to install Windows 10 preview and work with it today. I was running it on an old laptop (core duo, 2 gibi ram) and it ran ok, a little slow but not bad, very usable. Of course the preview version hasn't been cluttered up with junk and updates yet. I like the way it works. It's a good mix of the best parts of Windows 7 and 8.
The big new thing is the way it tries to compete with Google apps. They want you to login with a Microsoft online account, tied to the Microsoft store, and outlook, and calendar, and office 365, and etc, etc.
The design is clean and usable and so far it runs better than Windows 7 or 8.
Of course the first thing I did was install Google Chrome, Google Drive, LibraOffice, and GIMP. All running well.
Arranging the tiles to my liking took a few moments to figure out, but not bad.
I love the new task manager. It gives much better info. (maybe this was in Windows 8, I don't know. I use it so rarely)
It boots faster than I am used to for Windows. I'm hoping it stays that way.
So far the wifi is being more reliable also.
Fun Fun