We're seeing some cases where contention for the mailbox lock causes errors on Exchange 2013. In a post over on my new blog, I describe how to identify this situation: http://bill-long.com/2014/02/07/mailbox-lock-contention-in-exchange-2013/
In Exchange 2013, a member of Delegated Setup can't install Exchange if legacy administrative groups exist. I describe the problem over on my new blog, and provide a simple script to work around it:
http://bill-long.com/2014/02/04/delegated-setup-fails-in-exchange-2013/