Welp, this page was done entirely in GIMP, apparently. (Not entirely, mind: I still do every bit of lineart by hand.)
Overall, I like the program a lot. It does pretty much everything I need from an art program anymore, though a lot of it is still unintuitive to me. But I know most of that is just because I've got 12 years of Photoshop muscle memory built up in these hands. (There are still a few things that are just plain poorly designed, though - like moving the contents of selections. That alone is incentive enough to hurry up my transition to genuine hand lettering!)
But yeah, not bad for my first real foray into it. I spent about 3 hours coloring and lettering this page when it would have taken me half that in PS. All in all, I consider that a success, and I'll only get quicker as the hotkeys start stickin'.