I do street photography 96% of the time with Zorki and FED. I would say that they are user friendly and can be considered for serious work. It's the adjustment part which may turn off some people, but once these machines are
set, they can do work as good as any other camera.
The functions may not be as easy, but then again, any camera requires some form of learning curve.
In as far as cheap goes, the Russian and Ukrainian rangefinders are hard to beat. Just yesterday, our group went on a street shoot. Three of us shot with
Russian rangefinders. One dropped his FED-2 on the pavement. Nothing happened to it. Nothing happened to the owner as well. Just imagine if this FED-2's owner had dropped a Leica, a Bessa, or an R-D1 instead. He may have suffered more trauma than his camera did. 😀
I also had an R-D1 in tow. In as far as responsiveness goes, the Zorki fired and shot when it was commanded to. Film cameras still win in this category. 🙂
Jay