Quote from Anandtech:
"To put this in perspective, in the past few years I've reviewed probably 30-40 different displays, from PC monitors to TVs to projectors. Not a single one, out of the box, can put up the Gretag Macbeth dE numbers that the iPhone can, and perhaps one projector (which listed for $20,000) can approach the grayscale and color accuracy out of the box.
Apple obviously has very high control over what parts they use and what comes off their assembly lines. I don't know if they are having the displays individually adjusted after they are assembled, or if the quality control is very strict, or if I just got a remarkably lucky sample. I do know that if TV and PC Monitor vendors were able to provide displays that looked like this out of the box, professional calibrators would lose a good amount of business. The new panel in the iPhone 5 is simply remarkable in quality and if it were a PC monitor, I'd give it a Gold Award on the basis of its performance".
That is saying a lot.