Just a bit over a week ago a new version of the Master Data Services Add-in for Excel was released. It is the 2014 release, which will also work for SQL Server 2012. Main benefit is up to 4x performance improvement without any server configuration changes. If you need extra performance you can get 2x extra by enabling Dynamic Content Compression in IIS on your MDS server.
Here is the download page: http://www.microsoft.com/en-us/download/details.aspx?id=42298.