I went to the Privacy statement [0], to the "Reasons we share your data" (click on Learn More) and it does not sound scary at all (it' pretty much the same as any internet company that holds customer data). It's very clearly worded and I know exactly how/why my data will be used, so I can decide if I want to go ahead or if I don't.
There's also a Data Retention section further down that specifies how long your data is in their servers.
edit: In the top section (Personal Data we collect) it also says: "You have choices about the data we collect. When you are asked to provide personal data, you may decline. But if you choose not to provide data that is necessary to provide a service, you may not be able to use some features or services."
[0] https://www.microsoft.com/en-us/privacystatement/default.asp...
There's also a Data Retention section further down that specifies how long your data is in their servers.
edit: In the top section (Personal Data we collect) it also says: "You have choices about the data we collect. When you are asked to provide personal data, you may decline. But if you choose not to provide data that is necessary to provide a service, you may not be able to use some features or services."