As said in other topics, I had my first Kiev (a 1968-made 4A), back in 1975: it accompanied my first steps in photography and became my favourite camera; from 1981, working along with a Contax-II inherited from my grandfather.
That Kiev-4A perfectly works today (it was lubricated and controlled some years ago, nothing to repair): it took innumerable rolls of film in any weather condition.
With time, I've started to collect Kiev RF's and to use them of course: after a practical test on pieces from the earliest times (the 1947 Kiev of my avatar) to very late ones, I can say that the cameras made earlier than 1970 were generally better mounted, finished and technically controlled.
I can also say that my two Kiev-5, both work precisely and smoothly; their bulky appearance is compensated by a very fine viewfinder, with parallax compensation.
What was correctly noted, is that a camera with over than half a century of (often heavy) use in its mechanics, can be in need of the care of a good technician. RF Kievs are generally cheap to buy, but in my opinion, well worth the price needed to have them back in shape.
Best wishes,
Enzo (E.L.)