As you probably know, the screen size remained the same but horizontal and vertical resolution got doubled. This resulted in 2048x1536 resolution and thus much higher pixel density compared to the device's predecessor, as well as devices such as Asus' Transformer Prime, 11'' MacBook Air, 17'' MacBook Pro, etc.
In fact, the pixels are quite hard to discern on the new iPad. This speaks volumes of the efforts that went into increasing pixel density, and judging by microscope shots in the review, it paid off.
While resolution got a serious boost, brightness and contrast weren't that lucky. Namely, when it comes to these, iPad 3 is the same as its predecessor and not as capable as many of its competitors (whatever capable may mean in this case).
The guys tested gamut as well, and found that it significantly improved as well. Apparently, iPad 3 managed to represent 65 percent of the Adobe RGB gamut. In comparison, iPad and Transformer Prime were at about 40 percent. The new Retina Display also managed to deliver almost full coverage of the sRGB color gamut, again beating the competition and spelling hell for the competition.
You can find Anandtech's comparison of screens on, from left to right, iPad 2, iPad 3 and Asus Transformer below, while the full review can be found here.
Credit: AnandTech