When creating a new instance in Azure (this is my free trial account), there are 2 ways to do it - either 'Quick Create' or select an image from a gallery. I've tried repeatedly to create the SharePoint 2013 Trial instance from the gallery, but each time received an error saying "The value for parameter 'PersistentVMRole.MediaLocation' is null or empty."
However, I was able to 'Quick Create' a comparable OS and size machine with success.