For Configuration Manager 2012 R2 there are now two hotfixes available, remember to only install them if you are experiencing the issues described in the KB article.
“An update is available for the “Operating System Deployment” feature of System Center 2012 R2 Configuration Manager” http://support.microsoft.com/kb/2905002/en-us
This update solves two issues:
1. After you enable the PXE Service Point role on an instance of a specific distribution point, or you select the Deploy this boot image from the PXE-enabled distribution point property of a boot image, the Windows Deployment Service (WDS) stops running.
2. It solves a performance related issue when the image is downloaded during OS Deployment, this is only applicable if the task sequence is deployed as “Download content locally when needed by running Task Sequence”
“Per-computer variables for imported computers are not read in System Center 2012 R2 Configuration Manager” http://support.microsoft.com/kb/2907591
It solves an issue where computer variables are not read by the task sequence during OS Deployment for imported computers.
Additionally here is a list of all KB articles related to Configuration Manager 2012 which can be really useful to have a look at when troubleshooting: http://social.technet.microsoft.com/wiki/contents/articles/9539.list-of-public-microsoft-support-knowledge-base-kb-articles-for-system-center-2012-configuration-manager-configmgr-2012.aspx