If you are a fan of the Tessar gradual and buttery smooth transition out of the focus, it's a good lens to have. I would guess it has some imperfection wide open and gets super sharp as you stop down like tessars I've used on bigger cameras. That's the versatility and fault at the same time of the tessars. I use them in LF and think highly of them.
Ken Rockwell doesn't understand (or at least write about) things that are gradual and subtle and so forth. That's not his style. He wants it to be crisp all the time and produce velvia saturated vacation/kid photos.
If you like the size and shape of the lens, but not the throwbacks, sell it to a cult buyer/collector and get a Voigtlander 40 SLII. I have one of these because I wanted f/2, and I really really like it. Ken Rockwell likes it because it's one of the sharpest lenses available, and I like it because it's that and good bokeh and focus transition at the same time.