I tried out Windows 10 yesterday for a few hours. Aesthetically, it quite boring. Just more flat square blandness (I feel that Win7 was prettier). It was nice to unpin all the Tiles from the start menu, which is a huge improvement over Win8 start screen.
What I don't really like is the requirement of having an online Microsoft account and the defaults are a concern in relation to privacy. I especially hate the "Not recommended" suggestions Microsoft displays when turning off online connectivity for various apps. Then to uninstall pre-installed apps, you wont find them in the usual place (Programs section of the Control Panel), rather you need to go to PC Settings, Search and apps, App sizes. Maybe this will change, but for now it appears somewhat disorganized.
Overall I'm not really that impressed, the default pushes all things "cloudy", which to may appeal to some but not so much for anyone valuing privacy.