For me it's a case of being the worst open source image editor, except for all the others.

The scripts always seem broken, the UI was a mess for a while on a Mac. The multi windowed system was great if the windowing manager expected that sort of thing and terrible otherwise.

Ufraw integration seems an awful way of getting to edit raw files and I go years at a time without being able to get it working on a Mac.

But it's still my first choice.