I just got the 5D3, 24-105 kit. Good deal at b&h for $4,100. Awesome camera, very good lens. Great lens for $600 kit price. Color, resolution and contrast all look very good. The bokeh issue is evident in the second gravel shot. I've found the less detail the background has, the smoother the bokeh. On par with my 17-55 with a whole lot more res of course, but it takes a back seat in the bokeh dept.
Here are the samples I've based my findings on: