Interesting comments.
I have been shooting with the 50 1.4 for about 8 years, exclusively at 2.8. At that aperture, I have experienced none of the image quality concerns that permeate these comments. Mine is very sharp...it took four copies to land on my current version. However, once i go below 2.8, the AF pretty much goes to hell. And at 1.4, the image is a haze.
And i also own a 35 f2 IS- that was nicely fixed up by canon after being sold a broken lens. Um, yeah, my 50 is better than the new model 35 in both sharpness and bokeh. Boken for the 35 is not one its strong points- it is rakish at best, and oof trees and shrubbery can look pretty horrible at times.
That said I am curious why canon has not updated the optical formula for this, the 85 18 (and its UGLY purple hazey, wide open images). They have put in a ton of work for an L version, while the normal version lingers. The forums + customers for years have been begging for an update, and...nothing. 20 years old formula....it's just crazy.