I have used an M3 for the past 25 years. My first was given to me by my father, who in turn inherited it from an uncle. It was a very early (circa 1954-55) model, double-stroke, with the older speeds. Had a Summarit 1.5 50mm lens. After much use, I traded it (with some extra cash) for a single-stroke 1958 model, which I have used ever since. Lenses in my arsenal are a dual-range Summicron 50mm, 3.5 Summaron 35mm RF, Hektor 135mm, and Voigtlander 15mm Heliar (just purchased a few weeks ago). I updated the camera with a rewind crank and quick-loading film spool. Also just added a Voigtlander VC meter to replace my old MR meter which was not reliable anymore.
I love the size, quality and feel of the camera, and of course the lenses are the best around (although the expensive newer versions are sharper). I have used SLR through the years, and digital as well, and each has its purpose. But I still come back to the Leica. Many will gripe that it is manual-everything and hard to use compared to today's autofocus, auto-exposure cameras. But I still prefer doing it all myself.
Regards, Andy.