One of my all time favorite lenses. From tests I've seen online sharper than the 2nd version Leica Elmarit M.
It's sharp, but it will not be the sharpness per-se that will win you over.
There is something, at least to my eyes, in the way this lens treats the tonal values of an image and the out of focus areas (no, I'm not talking about bokeh, more about the areas that are not "exactly" in focus) that I find extremely captivating.
I have serious trouble leaving this one out of my bag. Luckily it is so small that I can tuck it in every small remaining space!
Many of them suffers from what, in large format circles in reference to another brand, is called "Schneideritis". Basically the glass will looks full of tiny bubbles (even though these should not be bubbles in the glass, but according to many just spot of antireflective paint coming off the "walls" of the lens).
This is my second one and it is clean; my first one, on the other hand, was affected pretty heavily by Schneideritis. Even so, the only thing I noticed with it was a certain propensity to flare more easily, but it was sharp as ever, in fact in my opinion probably ever so slightly sharper than the clean sample I have now.
Acquappesa marina in the winter, Italy
Storm clouds out of my kitchen window