Unfortunately I do not have any digitized pictures to show for, but believe me when I say I am mightily pleased with the pictures my collapsible Summicron takes. I am lucky to have one with near-pristine coatings.
I like the handling, too: as someone already posted one does not need to collapse or decollapse it all the time and just use it like any other lens; collapsing it just comes in handy sometimes. For a shade I use two 39mm UV-filters with the glass carefully removed. There are certainly more flare-resistant (modern) lenses, but in actual use and with a modicum of care I have never had a picture that was "ruined" by flare.
In some fast paced situations the long throw of the lens can make it hard to focus quickly, on the other hand the long throw is very useful for street in the sense of prefocusing and not having the crucial distances (3m, 5m for me with a 50mm) too close together, as with other more modern lenses.
Greetings, Ljós