I do not understand what new:
A new server level permission. Grant CONNECT ANY DATABASE to a login that must connect to all databases that currently exist and to any new databases that might be created in future. Does not grant any permission in any database beyond connect. Combine with SELECT ALL USER SECURABLES or VIEW SERVER STATE to allow an auditing process to view all data or all database states on the instance of SQL Server.
where is the improvement? could not do with sql server 2012 or 2008?
It would be helpful for an explanation with T-SQL?