Bugs are common in a DEVELOPER preview this isn't the release version give them time to iron it out.
Facebook integration removal sucks, but Facebook is responsible for that change not Microsoft, Twitter works like it did before which continues to point that Facebook demanded the change, and this isn't Microsoft took away on purpose.
Xbox Music isn't updated to Windows Phone 8.1 yet which is why it's buggy, give them time to update it before you claim judgement.
How is the ME title useless now? I can still check what's new in recent posts, I can check in, and still post updates directly in the app for anything but Facebook (Which wasn't Microsoft's fault).