Upload & Sell: On
Yes, all are correct, as far as I've experienced in using this lens in the last few days. The DOF at 1.2 seems to be hit and miss, and as Pompo said, if you back up from the subject, then it should give a better AF accuracy. However, if shooting up close, like in someone face, then I'll probably make sure that the subject be still, and will try to use manual focus and live-view, if possible (the big IF).
Also, 1D body or not (mine is 1DS3), the slow focusing is probably better than some other models, I do think that this lens focusing is pretty slow compared most lenses. But if you talking about slow focusing, compare this to other highly regarded lenses like the Zeis lenses on Canon body, all manual focusing, so the slow focusing is not too bad, just an option that if you choose not to use MF.
However, this lens is basically not your normal point and shoot, but a specialty lens, therefore just like anything, requires special handling and care, that is why it is fun to have.
Others who have used this lens for a long time think that we're talking about old stuffs here, but I believe that they were excited about this lens just as I do now, when they first got it, so don't forget that...
Yes, it will probably take me a few months to get used to it, but again, this is part of the fun that I do as a hobbyist.