I've been using it for the past month since I completed my build.

Cons:
-Crashes more than a released OS
-UI can be buggy at times
-Memory leaks

Pros:
-Free
-100% of the games I've played ran PERFECTLY
-Works with the latest WHQL drivers from AMD and Nvidia (haven't tested beta drivers though)
-HAS A FANTASTIC START MENU
-Really fast. 5 second or less boot times from the power button
-More stable than Windows 98

Anyways, so far, the only really bad thing that has happened to me so far is that experimenting with DSR'ing the desktop led me into an unbootable loop fortunately I had just installed new drivers, so I was able to use System Restore, but had to re-download a couple games (100/100 up/down so not too bad).

Other than that, though, my experience has been net positive! If you're looking into getting a new computer, I'd highly recommend at least trying Windows 10. The UI is fantastic, still like Windows 8, but more like 7.