There are very few changes in the SQL Server Agent in SQL Server 2012. Those who have used the SQL Server Agent in SQL Server 2008 will find that almost all the screens and functionality are the same in SQL Server 2012. In fact, the SQL Server agent has changed very little since SQL Server 2005.
There is, however, one feature that was removed in SQL Server 2012 that has impacted the SQL Server Agent. SQL Mail has been removed. This mail system was an option for configuring the Alert System that the SQL Server Agent uses to send notifications. Database Mail was added in an earlier version as a replacement for SQL Mail and is now the only available Mail System option.