If you have AF-issues with this lens, you need to calibrate it, calibrate your camera or stop using it at 2,8-4,5!
The AF of my 50 L beats the cr@p out of my 85 L, both speed and accuracy, and it's a lot better than my (now sold) 35 L. It's the best AF of any 50mm. Color and contrast from wide open is just fantastic. Where it struggles is when approaching MFD, due to the lack of floating elements. But shoot at 1-1,5m, and it's not an issue.
I read a lot of negative stuff about this lens, and people saying the "50mm f1,4 is just as sharp" Well, then you have either forgot to remove the lens cap or haven't tried it at all. It's lightyears ahead of the 1,4 when it comes to sharpness, where it counts, between 1,2 and 2,8.
Superb build! and weathersealed, which the 85 and 35 isn't, big deal for me! The only lens I like as good is the newly bought 24 L II, now with that lens you can talk about AF issues from hell, replaced two copies and I've read reviews and hear of many with the same problem, the AF was set to "random" with those copies. Now that I have a working one, in combo with the 50 L , oh wow....