Buried in the 12,000 words of Microsoft's service agreement (about the size of a small book) we find,
"We will access, disclose and preserve personal data, including your content (such as the content of your emails, other private communications or files in private folders), when we have a good faith belief that doing so is necessary to do."
What the hell?
Cortana has access to your camera and microphone, and more importantly, it has access to your contacts, calendar, and probably all of your documents. It reports beck to Microsoft & its partners. The Edge browser has Its own integrated PDF and Adobe Flash reader. Its support for asm.js, a JavaScript subset from Mozilla that has been attacked before.
A Microsoft account is mandatory for many services, including Skype. This gives Microsoft more potential to collect info on you.
Wi-Fi sharing defaults to on. That means you will be sharing your Internet connection with your neighbors if you leave it in its default state.
Sign into Windows with your Microsoft account and the operating system immediately syncs settings and data to the company’s servers. That includes your browser history, favorites and the websites you currently have open as well as saved app, website and mobile hotspot passwords and Wi-Fi network names and passwords.
Turn on Cortana, the virtual assistant, and you’re also turning on a whole host of data sharing. Cotana collects and uses various types of data, such as your device location, data from your calendar, the apps you use, data from your emails and text messages, who you call, your contacts and how often you interact with them on your device. Cortana also learns about you by collecting data about how you use your device and other Microsoft services, such as your music, alarm settings, whether the lock screen is on, what you view and purchase, your browse and Bing search history, and more.
Microsoft is always listening because Cortana analyzes speech data. Microsoft collects “your voice input, as well as your name and nickname, your recent calendar events and the names of people in your appointments, and information about your contacts including names and nicknames.
Realistically, Cortana can’t work in the semi-magical way it does without being able to gobble up all that information. But it’s worth being aware of just how wide-ranging its access to your and your friends’/contacts’ data is.
Windows 10 generates a unique advertising ID for each user on each device. That can be used by developers and ad networks to profile you.
There's a new telemetry system called "Asimov" which can be used to monitor the usage of any Windows 10 computer in real time, and if you agree to use Windows 10, you agree to let Microsoft monitor your computer at any time, for any reason, and to share any data they gather with their trusted partners. And no, you don't get to know who those partners are. They might even let law enforcement have access to what you're doing in real time. That might include access to your webcam.
If you're an attorney, what guarantee do you have that the law or other attorneys partnered with MS partners won't be reading your private legal discussions, patents for a client, etc.
I write my own software for stuff. What's gonna prevent some techie working with MS or their partners from stealing my ideas or software? A corporate or technical user's ideas, & designs for new products & campaigns may have to be kept secret until they're released. What if some of Microsoft's or their partner's staff are competitors in the same market, & they get to spy on our computers?
In million ways, this is very bad.
Then they wonder why most corporations, NASA, science labs, Cern, & HADRON are still using Windows 7 or XP. Ok, they may have something else on their personal pocket phone or tablet, but not on their work machines.