It's often said that the 28 1.4 is not sharp wide open.
What do you think of this 100% crop?
For most purposes, I find the 28 1.4 adequately sharp. If I need sharper, then either stop down or more light and a 'sharper' lens.
But as a wide angle, fast lens, the 28 1.4 is a gem, particularly for color/contrast and comma correction.