The program is no longer developed and supported. Last version, v5.16, released on April 5th, 2015, can be still downloaded from the official forum.
It does what I need it to do. The user interface is a little confusing at first, but not too hard to figure out.
UI is not the best but it does the job very well
Our users have written 2 comments and reviews about ExifToolGUI, and it has gotten 14 likes