SQL Server 2012 includes only a small number of significant updates to the core SSRS platform, which is not surprising considering the SSRS overhaul that came with SQL Server 2008 R2. The enhancements provided in SQL Server 2012 include the following:
An updated rendering extension for Microsoft Excel 2007-2010, supported both by Report Builder and the SSRS web rendering controls
An updated rendering extension for Microsoft Word 2007-2010
The ability to view web-based reports on touch-screen Apple iOS 6 devices ...