I liked it....
(The Schneider Curtagon)
I think Rodenstock also made 2 35mm lenses for the camera: I tried the 35mm 4.0 and wasn't impressed.
I liked my Retina IIIS. Drawbacks were: not as ergonomic as a Leica, limited to 28mm widest and the 85mm (Schneider) lens was unimpressive.