My Certo has a 75mm f/2.8 Carl Zeiss Jena Tessar, uncoated, in a Compur shutter. The camera is impressive in many ways, but it's a pre-war design and it shows. The body-mounted release button requires a convoluted linkage that can go wrong in about ten different ways. The rangefinder is a split-image type, which is hard to see in the best of conditions, and the mechanism is both crude and delicate. The VF and RF windows are very small, and framing is hardly precise. Since it's a dual-format camera (6x6 and 6x4.5), it's bigger and heavier than a dedicated 6x4.5. On the subject of format, you have to have a mask even for 6x6, since the rollers are built into the mask rather than the body.
That said, the build quality is very good, and the lens and shutter are fairly foolproof. Clearly, it's not the most user-friendly camera ever made, but it does take very nice photos if you can live with the quirks.