Microsoft SQL Server 2012 Integration Services (SSIS) provides significant improvements in both the developer and administration experience. This article provides tips that can help to make the upgrade to Microsoft SQL Server 2012 Integration Services successful. The tips address editing package configurations and specifically connection strings, converting configurations to parameters, converting packages to the project deployment model, updating Execute Package tasks to use project references and parameterizing the PackageName property.
Above text is taken from original msdn documentation.
Reference: Pinal Dave (http://blog.SQLAuthority.com)