A comment in another forum about the current Summicron was that one received a dermatology lesson with every picture taken with the lens. I've been through two of the current ones and now use the current Elmar-M 50mm which is a little warmer and not quite as sharp as the Summicron, and the pre-ASPH Summilux 50mm which I think is in a class of its own. What a great lens and boy does it get criticised just because its an old design.
I really like the older designs from the 60's & 70's - they have a little less contrast, may not be as good with flare, and manage to produce beautiful transitions yet still be sufficiently sharp to produce hight quality pictures. I have a Jupiter-8 from 1959 I think and that is also a great lens, so it isn't a question of the cost of the lenses.