While the claim is true, it’s also true that this ability is not a secret. Anyone who downloaded the OS for testing was presented with the Privacy Statement first, and it explicitly says that “when you acquire, install and use the Program, Microsoft collects information about you, your devices, applications and networks, and your use of those devices, applications and networks.”
“Examples of data we collect include your name, email address, preferences and interests; browsing, search and file history; phone call and SMS data; device configuration and sensor data; and application usage,” Microsoft points out.
“For example, when you install the Program, we may collect information about your device and applications and use it for purposes such as determining or improving compatibility; [when you] use voice input features like speech-to-text, we may collect voice information and use it for purposes such as improving speech processing; [when you] open a file, we may collect information about the file, the application used to open the file, and how long it takes any use it for purposes such as improving performance; or [when you] enter text, we may collect typed characters and use them for purposes such as improving autocomplete and spellcheck features.”
Regular testers know that using Technical Previews of software means that data about this use will be collected as its needed to improve the final version. Also, that Technical Preview versions are often buggy and altogether insecure, and not fit to be used for handling sensitive data.
Finally, these capabilities will be removed in the final, commercial version of the product, so don’t panic.
Microsoft has reacted to this ruckus by releasing a statement reassuring testers that they “all data sent from the Windows 10 Technical Preview to Microsoft is encrypted in transit and we store the personal information you provide on computer systems that have limited access and are in controlled facilities.”