A fine high value zoom lens. Stabilisation was a problem until I used the Sigma dock and put the OS into the Dynamic mode setting - magic, then it's as good as most Canons' IS. I would assess the Sigma 150-600 C OS benefit as 3.5 stops.
Still decently sharp at 600mm (F8-F11) Autofocus works well on 6D Excellently sharp between 150mm to 430mm Really gives the Canon 400mm F5.6 L a run for the money at 400mm
None at price point (A bit soft in the corners at 600mm FF; but hey its as good as the Canon EF 400mm F5.6 L which has no IS and about costs about the same and better the Tamron 150-600mm at 600mm