I just overhauled one a few weeks ago and I am falling in love with this lens! it's a true "Tessar" if I can say that. Not only does it share the same formula but it also has the "same" trait of being sharp at the center and "poor" at the corners by design. I love Tessars and discovering this made me really happy!
specially if you consider that I got this for a cheap price (from Alps-do, of course).
here are some pictures