Work in progress
Given that Windows 10, desktop Office and Office 365 all come from Microsoft, you would expect a smooth experience when using all these products together. Windows 10 represents significant progress.
You can sign in with an Azure AD account, and get single sign-on from the Edge browser and from aware applications, including Mail and Calendar and the Office Mobile apps, though not yet People.
The experience is still not as good as it should be, thanks to continued dependency on the Microsoft Account in some parts of Windows 10, the poor OneDrive for Business sync client, and lack of Edge compatibility in parts of the Office 365 site itself.
Fixing Store access and the OneDrive for Business client will address most concerns, though some confusion over organizational versus Microsoft accounts looks likely for the foreseeable future.®