I find the UI of recent versions of GIMP to be very nice for the simple image editing / processing that I do.
I think a redesign of the icons was necessary, because the old ones don't look amazing. But you can make tasteful icons which are also colorful and recognizable.
(And I know you can switch icon themes, but when we're talking about UX, we're largely talking about the out-of-the-box experience. 99.9% of users are going to stick with the default icon pack.)
> (And I know you can switch icon themes, but when we're talking about UX, we're largely talking about the out-of-the-box experience. 99.9% of users are going to stick with the default icon pack.)
That said, Photoshop also uses monochrome icons and it can help in some ways to avoid distracting from the image which you are working on. I am not sure what the best compromise would be.