The only problem, but this will change from sample to sample, is a big lack of consistency when focusing at full aperture, that one cannot even correct in camera because it varies randomly from front focus to backfocus and in intensity.
It will blows away most pro zooms, and a bunch of primes. Yes, L types too.
100% crops. Left center, right borders (on Canon 5D Mark II):
No excuses to not have one in your bag if you shoot Canon, especially for DX owners that may use this like a fast portrait lens.
And did I mention that NEW it costs merely 100 euro?