OneDrive (the storage service for Office 365) is no longer unlimited, instead you will have to make do with a measly 1TB maximum. Microsoft have also reduced the free storage from 15GB to 5GB for personal users. Google Apps for Education will be worth looking at if you work in the education sector as that is still unlimited storage.
Apparently Microsoft have got the hump after some users were storing 75TB on their unlimited storage account, the cheek!
If you are currently using more than 1TB (education or paying customers) or 5GB (personal) you have 12 months to move the data elsewhere.