Having deployed different Office 365 workloads often makes you want to get some statistics on how the services are used.
You can find quite a few reports for most of the services in the reporting part of the admin UI. 
The most common ones used are the inactive users and mailboxes reports, but there are also reports on how users are utilizing Lync Online, OneDrive for Business etc.
What not so many people know about is that all these reports and some more are available through Exchange Online PowerShell as well.
As seen above, we have 61 cmdlets related to reporting in EXO PowerShell, some of them quite interesting. For example, Get-LicenseVsUsageSummaryReport, that will give you a brief overview of how many active users you have compared to the amount of assigned licenses. Detailed information about the cmdlets can be found here.
Active users per workload in comparison to the amount of licenses assigned to the tenant.
Except the report above, two reports that many of my customers schedule and send out as an email to to admins, are Get-StaleMailboxReport and Get-StaleMailboxDetailReport. Those reports can in many cases help us avoid having to use Get-MailboxStatistics that has been the only option earlier.
Happy reporting!
/Johan
