There is an old adage that is much easier to write a sad song than a happy song. Maybe why Pink Floyd was so good at what they did!
Much of the reviews of this lens seem to revolve around a bad experience or the price being high. I am sure that most people who are experiencing good things with this lens aren't writing reviews, they're probably taking photos.
My copy, right out of the box, gives me images that are sharp, contrasty, and in need of minimal post-processing. The only other lens that I have that is similar is a 50mm 1.4. All of my other lenses need a bit of help.
Additionally, this lens focuses very quickly and accurately, almost never a hitch.
The only other lens of the third parties that I thought was pretty good was a Tokina...but even though that lens was built well and half the price, the L took the prize due to the focusing and uber-quality. Sure maybe the image quality is only 5% better, but the other facets of this lens make it (so far) more reliable in its performance.