I've bought myself a used Sigma 30mm f/1.4 DC DN for my Sony a6000 this winter, but I have not had a good opportunity to get the potential out of it before 17. May, our National Day. I am really happy about the optics, but the focus by wire system (the focus ring is not mechanical) is a bit paint. If you most often run on auto-focus anyway, this is a great bang for the buck.
More from the National Day here.