The good thing about classic glass is that if you are not that fussy about having the fast stuff, you can put together a set of, say, Summaron 35/3.5, Elmar 50/2.8 and Elmar 90/4 for less than the cost of a single modern Summicron 50.
In good light, stopped down to f/5.6 or so, you have a compact, versatile kit that is capable of good results and feels nice to work with. You can choose to accept the lower-contrast 1960-s look, or you can compensate with development/post production.
Wide open... oh well. You get the occasional flare and lose some resolution, especially in the corners. With faster glass you also get clouds of sickly swirling donuts (appreciated by some of the bokeh aficionados, though - YMMV) in OOF areas.
I've found that the stuff that I like among my photos is usually either daylight stuff or photographed from a firm tripod. So having slow lenses or lenses that need to be stopped down is not such a big problem. Not having money is, on the other hand, a big problem.
Obviously, you can get modern, technically excellent Japanese glass for similar money as the Leitz oldies, so it is not simply a practical decision. For me, there's something pleasant and comforting about using gear that could have been used 60 years ago, immerse myself into the old working methods and get good results. I guess it's a way to distance myself from today's computer-driven, computer-designed, robot-assembled, toy today - trash tomorrow kind of world. I have digital cameras, modern lenses, computer and software for addressing practical tasks but my personal photography is hardly a practical matter.