Emet v4Beta was first introduced here on the Microsoft Security and Research Defense Technet Blog. I have deployed the v3.5 tech preview to most of my secure workstations, so I inquired about upgrade paths and it looks like you should uninstall previous releases as well as delete the Emet registry keys before installing Emet v4 Beta. The registry keys to delete are located at "HKEY_LOCAL_MACHINESOFTWAREMicrosoftEMET*"
If you want to download the Beta version, here is a link to the download page. I have just begun testing out this new version, and so far the best feature that is now included is the option to only audit and not crash the program. Also, when an application trips a mitigation response, you can see one or more little boxes that pop up in the lower right hand corner of the desktop, and in some cases the boxes quickly blink and scroll up the screen as the exception happens multiple times. Then you can go into the EMET control panel and turn off the mitigation that is mentioned in the box if you want the program to continue to run despite the issue.
For example I have only had problems with the SimExec mitigation, and it has so far affected Internet Explorer and Microsoft Word 2013. I went in and disabled the SimExec settings for these applications and have not had any more problems running Word or IE so far. Once you install the Beta you can read the manual located in the Program Files directory.