So...I have it in hand...
It is a chunky lens. A little larger than the 23/1.4, but not hugely so. It's lighter than it looks, though. The focus ring feels beautifully damped and smooth. The aperture ring is OK. It's not loose like the 14mm ring, but it's not as tight as the 23mm, 35 and 60 that I have. Detents feel a little shallow to me, especially on A (not that I'll ever use it there), though the f/1.2 detent is good. I can move the ring up and down slightly, though. In 'feel' it's probably closest to the 23mm ring.
Autofocus is quick but not blazing, and it can slow down if focusing on closer stuff. Don't think it's going to break records, but it's not bad. Focus isn't as quiet as the zooms, but it's quieter than the other prime lenses for the most part.
Optics: I've only shot a handful of shots around the office really quick, so I can't comment too much, except to say that it's more than acceptable at f/1.2. It's about the same as the 23mm f/1.4 is wide open, which is pretty darn good. Contrast isn't really biting at f/1.2, but it's pretty good overall, and resolution is quite high as well. There's some CA that's present when opening in PN, though Lightroom corrects it instantly with no problems.
Some quick test shots, all at f/1.2:
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(close up)
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