NO i'm not saying 24-105 is not good. just its mediocre bokeh.
I disagree - the shot from wickidwombat suggests the bokeh is decent (not great, but decent). I don't think you're really talking about bokeh, but instead referring to the quantity
of OOF blur (bokeh is the quality of that blur, not how much of it there is).
You can certianly get a decent amount of OOF blur with f/4, if you have a close subject. Another example:
EOS 5D Mark II, EF 24-105mm f/4L
IS USM @ 105mm, 1/160 s, f/4, ISO 100