The 85L only stops down to F/16, and hits its maximum sharpness well before that. I took a few shots with it at F/8, and was floored by the sharpness.
Original size, so you can pixel peep your heart out.
Generally speaking, any good prime is going to have better optical performance than a good or even great zoom. The 85L is one of the best SLR prime lenses, period. In skilled (and/or patient) hands, it can deliver a great picture of nearly anything that's holding still. If the subject is moving, you'd best look elsewhere.