Summary: As other reviewers have stated, it's super blurry and vignetty in the corners at f/1.4. However, it is extremely sharp at 5.6 and higher, and the image is gorgeous.
Pros: Consistent Output, Durable, Easy To Use, Fast autofocus, Good Image, Lightweight, Super fast
Cons: Blurry At Large Apertures, Plastic But High Quality, Vignetting At Large Apert
Summary: Wasn't sure if I needed to step up from the 50mm 1.8, but glad I did. This definitely feels far more solid, the focus is faster and smoother, and the overall quality is...
Pros: Consistent Output, Durable, Fast autofocus, Low Light, Nice bokeh, Solid construction
Summary: I upgraded from an old 50mm f/1.8 and use this 50mm f/1.4 lens on my 60D and 6D, along with a 70-200 f/4 L IS, a 85 mm f/1.8 and 24-105 f/4 L IS standard zoom.
Pros: Consistent Output, Lightweight, Sharp Fast A Must Have, Versatile