Every time I need to use Gimp to make a collage of two screenshots to file a bug report I want to smash my monitor and throw it out of the window.
Gimp workflow/UI just does not stick in my brain. I can get back to using Photoshop after skipping a year and it will feel like I've left yesterday. With Gimp it is always a painful 15-minute struggle to figure out the right combination of controls to press.