What I am really enjoying about the 21/3.4 Super-Elmar-M ASPH is its impeccable lens performance along with its superb contrast.
See my handy list of Leica gear, with color-coded prices for in stock status.
With the 21/3.4 Super-Elmar-M, one chooses aperture strictly on desired foreground/background blur (depth of field), and the lens simply delivers a world class result at any aperture, free of flare, and with minimal distortion.
The 21/3.4 SEM is a must-have lens for anyone with an M9.
A few examples late in the day in early November below.