I have never been a huge fan of GIMP. I always felt it was a cloud of functions barely glued together by an interface with an insane amount of cooks. However recent releases have resulted in a far better, if not ideal, interface. However on Windows in particular it has the old school Windows 2000 look, by default. You don’t have to put up with this though.
Above is an example of how it can do with a few minutes downloading and configuring. The theme is The Days of Grays by liliumcruentus it is pretty nice and gives GIMP a modern lightbox style dark interface.
Download the zip, unzip it, open the folder and go in and find the “gtk-2.0” folder, rename that to “The Days of Grays”, copy it and go to “C:Program FilesGIMP 2sharegimp2.0themes” pasting it there. Fire up GIMP, go to edit/preferences/theme, choose “The Days of Grays”. Ok and close GIMP, start it up and Bob’s your uncle, you are looking at a much better looking GIMP. For the darker grey image window, go to edit/preferences/image windows/appearance and set the custom padding color to 202020 in both cases.