I had enough focusing issues with my nikkor 35 1.4g that I finally got rid of it. I will purchase this eventually.
Keep in mind, with the new USB dock sigma has, you can fix focus problems by yourself beyond just using microfocus adjust on your camera. With the sigma dock, you can actually correct front/back focus for different amounts depending on what part of the focal range vs MFA on your camera is a one trick pony.
If you shoot nikon, get this lens, the nikkor 35 1.4g is not worth the price and not as sharp as this lens.