SQL Server 2012 SP1 Cumulative Update 4 incorporates fixes to 41 issues. It is available to download form the following knowledge base article link - Public KB Article.
In addition to the fixes the CU contains the following improvement:
Power View Connectivity to Multidimensional Models
Power View connectivity to multidimensional models - enabling you to leverage Power View against existing multidimensional models. SQL Server Analysis Services multidimensional models (a.k.a. cubes) provides in depth analytical capabilities empowering customers to answer questions with their data. Marrying this rich information sources with the stunning visualizations capabilities of Power View now provides you with an explosive opportunity to not only visualize their data but a better understanding of existing or emerging trends.