Last week I discovered a new bug in SharePoint 2013 and Office 365 (2013 experience). When you upload a file to SharePoint using the upload button in the ribbon you get a dialog where you can fill in some version comments. These version comments aren’t stored in SharePoint when you check in the file you uploaded.
Steps to reproduce: http://www.stefanfeenstra.nl/sharepoint-2013/bug-version-comments-not-saved-sharepoint-2013/
When you follow the same steps in SharePoint 2010 the version comments are stored in the version history.
I’ve had contact with Microsoft Support they gave me two workaround options:
1. Disable the option: require to checkout in version settings
2. Publish a major version and add some comments
They also forwarded this problem to the production team of SharePoint. But it’s not sure yet if they will solve this problem.
Please keep this in mind when you heavily rely on this functionallity.