After upgrading I realized I am missing some external plugins I had installed.
Those I am missing are ones that I had in an external folder that you could set in preferences. The ability to set an Additional Plugin Folder is gone. Can I set an external plugin folder?
It's in the FAQ. They've binned it as it apparently caused more problems than not. You have to reinstall all your plugins from scratch.
That does not work for TopazLabs plugins as their installer does not install the links into the proper folder in PS CC.
I copied the appropriate links from PS CS6 to C:\Program Files\Adobe\Adobe Photoshop CC (64 Bit)\Plug-ins
and restarted PS CC -- voila now have my four TopazLab plugins fully functioning again.