All of Canons 50mm lenses lack something, maybe except for the 1.2L (which is in turn quite expensive).
Funny you. How about focus consistency (and a fix for the focus shift problem)?
The 50L also lack sharpness when shot wide open, at least if you compare it to the wide open sharpness of other L primes.
Never seen the famous focus shift and is sharp at 1.2.
Sorry to break your illusion, but all 50L's are suffering from focus shift, even yours.. And no, it is far from sharp enough at f/1.2.
35L, 85L and 135L kills it in terms of wide open sharpness.