He was unique. My missus and her mother got to know him quite well, unfortunately, he wasn't at the Space Fest that I attended. Only three CMPs left now... I feel lucky that I've got to meet the astronauts that I have.
A humble, humorous and articulate man. I loved his book "Carrying the Fire". Its one of the best descriptions of spaceflight, covering his early flying, then Gemini and Apollo missions. RIP Mike Collins, gone but never forgotten.