My fiancé interviewed this morning in Bogota for a K1 visa. He had a good experience, though he had to wait for a few hours. Once he was called up his interview was <10 minutes. They asked him what countries he's lived in (he's lived abroad) and when was the last time we saw each other (just 3 weeks ago-- he felt like that helped). And that's it-- visa approved, they didn't ask for pictures or other relationship evidence. Good luck to all!!