Ex-Owner (4y), Neutral.
I think "better than most people think, but still massive room for improvement" sums up my experiences with the Mark II's AF.
For everything reasonably still, i.e. anything that is still enough to perform a focus-and-recompose with the center point, the Mark II's AF is fine. I never had problems even in low light situations. I took a couple of months to get the focus-and-recompose movement into my muscle memory. Initially I was pressing the shutter a tiny bit to early, adding motion blur due to camera movement.
But once things start to move (think kids, a couple walking down the aisle) and you are unable to use the center point things get nasty. Having performed the switch to the Mark III I now feel like I am in AF heaven.
Aside from moving subjects I found that for me not being restricted to focus-and-recompose added almost a stop of light that I can hold the camera still enough to get decent shots. It's just easier for me to keep the camera reasonably steady with one of the outer focus points on target.