Seems like yes, despite assertions that it is not.

Quote

“We collect a limited amount of information to help us provide a secure and reliable experience. This includes data like an anonymous device ID, device type, and application crash data which Microsoft and our developer partners use to continuously improve application reliability,” Myerson wrote. “This doesn’t include any of your content or files, and we take several steps to avoid collecting any information that directly identifies you, such as your name, email address or account ID.”

Moving right along, Myerson confirmed that Microsoft would love to collect words and phrases that you type – something we’ve known about since the first Windows 10 Technical Preview shipped – but explained that it’s not about advertising. Rather, it’s about being able to “deliver a delightful and personalized Windows experience to you.”

The Windows 10 Privacy Statement gives examples of data that Redmond might collect, including “name, email address, preferences and interests; location, browsing, search and file history; phone call and SMS data.”

So basically, use Windows 10 and your life is an open book to Microsoft and their partners. No thanks!