Our Spanish long time friend Valentin Sama has been the first to post a full Olympus 12mm f/2.0 review! You can read it at DSLRmagazine (Click here). In short we can say the lens has an awesome mechanical and optical build quality! And we all really appreciate that we can have some nice pro lens in our m43 lens system! The distortion is low and very harmonic (will make it very easy to correct). The diffraction is very high at f/22 making that aperture pretty unusable. There is a bit of astigmatism on the corners but nothing to be worry about. Color aberrations and Vignetting are almost non existent. The autofocusing with the lens is incredibly fast and manual focusing very precise. According to Valentin this is the best lens tested to date!
Thanks Valentin for being the first to test the lens and thanks Olympus for finding the way back to your strenghts (at least with the lenses!).
UPDATE: “Uwe” sent me this: Diffraction has nothing to do with the lens itself. It is only defined by f-stop and pixel size. Making a not about f/22 for a m43 lens does not relly make sense. I think m43 with 16MP sensor is easily diffraction limited at f/8.