Conclusion: Okay, it is an excellent lens, especially in combination with the 6D at low light level. But is is larger than I thought (I did hope it'd have the size of a 28/1,8), and vignetting is quite significant. Up to now (Feb. 5, 2013) I did not find any any lens correction data for the camera or with EU or DPP. On APS-C, in combination with a cheap rubber lens shade, it is good lens for street. Even here, the IS helps!
Pros: Fast auto-focus, Superior build quality, Super-sharp images
Summary: Great lens for a great price. Sharp images, nice bokeh, light, and sturdy. I have not had severe chromatic aberration problems. The autofocus is very noisy, but has no problems and is moderately fast. Purchase before this lens stops being sold! It is an older model.
Summary: I really love the lens' crispness and color contrast. It also seems to be of high quality build, including a metal mount. My only complaint is that the bokeh is not extremely smooth due to the 5 blade aperture. Works well as a general use lens on an APS-C sensor camera due to the 1.6x focal length magnification. Does well in low light due to the large f/2 aperture.
Summary: My f/3.5-5.6 super zoom is great for nearly any situation, but it can force me to use unacceptably long exposures when I'm shooting indoors under available light. This f/2.0 lens covers that gap, and I can "zoom" it very effectively by just stepping forward or back a little bit. Canon's 55mm alternative is cheaper, but at typical indoor picture-taking distances, its narrow field of view would usually restrict it to head-and-shoulders shots.