Thanks everybody!
@PhotoComix
I use both. MyPaint feels quicker for the painting process, and I like the selection of brushes. I use GIMP mainly for textures and lighting effects.
@AnMal
I think it'd be fun to draw the inside

But I need more practice with interiors. I guess I won't get practice by not drawing something, though

@Erisian
I started with GIMP five years ago, about this time of year - so one less year than I've been married.
Here's a drawing I did then


And some more:
http://www.anorthogonaluniverse.com/201 ... niversary/@ he4rty, Mokonafan
I think I underestimated how hard it is to apply textures. This is one of the first textures I'm pretty happy with

I have a lot of misses, though.
@ Caz
I had some help with Sketchup for the perspective, which might explain why the tower looks like it's leaning. AnMal pointed that out in the WIP). There's a slight downward angle to the camera. I think next time I'll stick with two point perspective.