My understanding is that Ginger HDR is based on a dematrixing wrapper. It loads raw files into the wrapper that can then be viewed in prempro and AE. There is a utility provided that can be used to create the wrappers outside of these apps as well.
Ginger HDR also comes with a couple of plugins that allow tonemapping. I believe these were specifically designed for HDR time lapse but can also work well on raw files which can have values outside the standard range.
The plugins are also an interesting, if number heavy and intricate, way to colour correct your raw (or any) clips. They can do things many standard colour correcting tools can't such as faux HDR and adjusting just the shadows, midtones or highlights in a way I haven't seen outside of a heavy duty cc app like Resolve or Speedgrade using qualifiers etc.
One of the compositors I came across at work sometimes uses Ginger HDR on computer generated high dynamic range renders which have been output in EXR format, particularly if he doesn't have access to Nuke.
One problem I've seen is that if Ginger HDR is installed in AE, it takes over ownership of raw files so the ACR workflow is not possible. There is a separate plugin folder for PP where it can be installed which allows you to use Ginger HDR in PP but leaves AE with the ACR method.
Note, this is a different location to the standard media core plugins, used for both apps and Media Encoder, for Win 7 the main folder is found at:
C:\Program Files\Adobe\Common\Plug-ins\7.0\MediaCore which installs Ginger HDR to both AE and PP.
Whereas the PP only Win7 folder is:
C:\Program Files\Adobe\Adobe Premiere Pro CC\Plug-ins\Common
