Well after a day of issues at uni, my opinion is that somehow, microsoft took a pretty stable and functional operating system, and have absolutely nuked it. Until the most recent preview build, I didn't find any reason not to use windows 10 as my sole OS, since the update though, it's barely usable. Frequent lockups requiring hard resets, applications experiencing many many bugs, often to the degree that a different application has to be used, and most annoyingly, often when i log in, if i open an app too fast, then windows will not "load", and if i minimize the app (which is noramlly just a solid block of colour, there is no OS behind it, just a blue screen. If i ctrl alt del and select log off, it just goes to a blue screen, and if i hold the power button, instead of the thing sliding down over half the screen saying drag down to shut down, the screen just goes white. Not turning on after sleep. You name it, it seems to be happening.
Good job MS, you implemented cortana and continuum, both very poorly, and completely broke the rest of the OS as a result.