On a practical level I use the phone whenever I disassemble something new so I can refer back to see where parts go, etc. especially good for guns and electronics. I also use it to read my water meter which is underneath a sink in the dark darkroom (turn the phone light on, blindly take a shot and I usually get the numbers on the first try). But most useful is that I now pretty much photograph all the junk I swap on eBay and forums. The iPhone photos, reduced to ~1800 pixels, show just enough detail to be descriptive without being overly sharp or showing distracting dust. With the super camera every dust spec shows and even though I have a million positive feedbacks the proles will ask me whether the glass is clean, etc. so it's better just to show a smooth shot so they don't get hung up on nothing.
Beater Leica II with beater Nickel Elmar. Everything works well but the original 84-year old covering stunk of sweat and cigarettes (I guess? I hope the original owner wasn't an axe murderer) so I stripped it. I've had various recovering materials before but they always look too perfect so I'm going to see how well paper photographic tape works. Might put another layer on and let it age a bit.