I had used this lens when I had a M6. I have to say while a great lens, better than any Japanese SLR lens, it did not offer the magical "Glow" I have read so much about. I have an old 40/2 Summicron for a CL that I liked better.
Excellend lens; good bokeh; sharp
A touch flat when compared to Zeiss glass; Not legenday sharp as some claim