I was interested in this lens when it was announced more than a year ago, but now... It's too big(for M) and too expensive for a lens without AF(it's much higher than Samyang 14 2.8!). This one should be perfect optically to be considered.
I had a great expectations for RX10 and I was on a Sony presentation to touch it few days ago. Now I'm not so exited about it - it's uncomfortable for my hand, manual zoom with motor is very annoying, the pictures taken at 1600 ISO were with bad details(the sensor is between 1/1.7 and APS-C, but for me the details were closer 1/1.7(G15)), the focus could be faster.
I'll wait for new lens for my EOS-M when I want a compact camera.
Great!I was thinking about 10-12mm EF-S prime for a while and I don't think MF is problem on ultrawide lenses. If it's good quality and cheaper than 14 2.8 I'll go for it :)