I use mine on the 5D3 pretty much all the time unless I really, really need razor thin DoF. It autofocuses as fast as any lens I own and its minor deficiencies are easily corrected by Lightroom. I Even shot an available light concert a couple of months ago with it because I needed the zoom more than the extra aperture of my 50 1.8.
I use it on the 7D for a little extra reach compared to my 17-55 in sports shoots. It happens to work beautifully for certain events and venues. It may not be quite as sharp as my 17-55 but I don't use it for pixel peeping.



