I've been working with Windows 10 for almost a year now. The earliest versions of 10 impressed the heck outta me because the the installation was to fast and effortless. The presented product worked better than its Win-8 predecessor. One of the issues that used to occur with every new version of Windows was a healthy jump in the hardware requirements. With Win-10 I was installing onto 6 and 7 year old machines without any apparent sluggish performance hit. On brand new hardware it just screamed.
But there was issues, troubling issues. The "Metro apps" like the store, mail, maps, weather, etc, all required you to log into a Microsoft account (MSN, Hotmail, or Live). They simply wouldn't work without one. I made the mistake of using one of my existing accounts and discovered that it busied itself copying all of my personal data to the "cloud". So I purged the backup and deleted that profile from the computers and then created a dummy account for testing.
The next thing I discovered was that I had no control over Windows Updates. I've always measured the patches and updates and only installed what I thought important (I recognize that not all people are interested enough or technically savvy enough to do this). With Windows 10 they took away the selectivity feature and busted off the gate valve in the wide open position. "So where's the harm?" one might ask. For me it came in the form of an system update. I came home one day and realized that, in my absence, the machine initiated a 4 gigabyte download of a new version of the evaluation software. Since that machine is on metered internet it exhausted the entire month's data plan overnight. (when I'm doing something that data intensive I usually take it to work and use their data plan ;')
The WiFi thing was the next blow to my confidence of their new OS. We had already been hit by Comcast's idiotic data-sharing scheme. If you haven't heard about it the idea is that if you are a customer and if you own a laptop then Comcast would like to make it easier for you to be mobile. So if Comcast detects that you are in the presence of another Comcast hotspot it will connect you. In other words it opens your router to use by anyone who is a Comcast user. Notice I said user and not subscriber. If a subscriber gives the password to connect to their router to anyone, that anyone can now connect to your router. Neat trick, eh?
Microsoft is looking to do the same thing.
I've done a 180 on Windows 10 and now recommend that people do not upgrade - at least until some of this bullsnot is ironed out.