Just tested your new installer (Windows 7 - 64 bit with Gimp 2.8.20)
The .exe does not work (it is not even available in the Filter menu).
Here is the message (translated from Italian into English) which pops up when I fire up Gimp:
gmic_gimp_qt.exe - impossible to look for it
impossible to look for (not found) pthread_setname_np as regards the procedure for the dynamic link libwinpthread-1.dll.
On the contary your Zip works fine (as usual, I set myself its path with Gimp 2.8.20 later on).
As proposed by Garagecoder it would be extremely useful to have an option to set your theme (e.g. with Gray as Background).
At present, on Windows 7 the new icons (e.g. to zoom in - out in the preview window) are hardly visible.
I have recorded a video to show this problem: