The Azure AD administrative units are in Preview since a while, but lastly they got an update and I decided to check the opportunities that it might gives. Right from the bat, this feature has still a lot of possible improvement, I list those which would affect me the most at the end of the blog. But beside this, there are some neat use cases where I would configure Administrative Units.
Protect service accounts
Since the user administrator role can reset nearly every users password within the Azure AD (exceptions are Global Admin role members and more, see Azure AD User Administrator; thanks to nicola for the correction), it is very unlikely that you want to have a lot of administrators having that role. With Azure AD administrative units, you can add add regular users to a administrative unit. On this administrative unit you then can safely assign the User Administrator role to a technician, without giving the opportunity to gain access to an account with higher permissions. The following roles can be assigned within an administrative unit:
You can add a user to multiple administrative units, which allows to create a well designed delegation model for users and groups in Azure Active Directory.