The Office 365 Adoption content pack using PowerBI is now in preview for first release tenants. I’ve just switched mine on so it will be interesting to see how it looks. Of course there is only one user in my tenant so the data is not that useful for me as such. But for any organisation using Office 365 they will now be able to see (in an easier way) what parts of Office 365 their users are using.
Currently it runs on a monthly cycle so it is refreshed every month. But that is fine to be able to show data and analytics about user adoption. You will be able to see gaps in usage or over use perhaps in other areas. Maybe Outlook is still dominate. Maybe you need training. Not perfect by any means but it will provide some insight into the value you are getting from Office 365.