After finishing a roll with the Konica Auto S3, I finally understood what all the fuss was about rangefinders. It's a very different experience from using an SLR. Maybe it's the small size or the silent shutter. There's just something in the Auto S3 that makes taking pictures feel like a part of every day life.
The small size does help. It's easy to carry around and most of the time you would forget you even have the thing hanging on your neck. It's compact and stealthy and it gets you right smack into the middle of the action without turning heads. You consciously know you're not using an SLR. That alone lifts off some seriousness in your shooting. It just feels casual and even your subjects react that way.
Add in the super silent shutter and you have a very sneaky combination. Your subjects will never know you already took that photo.
The key difference you will immediately notice coming from an SLR is of course the viewfinder. You're loosing that through the lens (TTL) view, and instead you get an offset view from the rangefinder on the top left of the unit. That means you always see things away from the lens; you cannot see the filter effects, and most evident, you will always most certainly forget that you still have your lens cap on.
The focus mechanism is interesting and is really the component that gives the rangefinder experience. It gives a split image in the middle of the viewfinder that you have to align to have things in focus. You then adjust your frame to compose your shot.
There is a reason why most street shooters prefer a rangefinder and I get what they're going for. It's slick and stealthy, never wanting the public attention unlike SLRs. People don't take you seriously when taking pictures giving you freedom to shoot away. The silent shutter never gives a clue your taking your shot. And the rangefinder focus keeps it all fun to use. You still have all your manual controls to tweak to your content, but somehow, shooting with a rangefinder takes away the seriousness and concentration that an SLR demands.