Does anybody own the Sigma 150-600/5,0-6,3 DG OS HSM ?

I am interested in the Sigma 150-600/5,0-6,3 DG OS HSM.
Does anybody of you own this lens?
How is the AF and the image quality of this lens >400mm?

I am photographing with the common 100-400 Canon lens, somtimes with an converter on. But then the quality sucks a lot. Is the Sigma better in the high tele area?

G, Daniela