Do you know what an IPS screen is? This acronym means ?In-Plane Switching?, what I would translate as ?the image doesn?t pump when you move a little bit in the position of the screen?, or as ?there is no 'right' viewing angle? (the most technical explanation, I leave it up to Wikipedia), and allows LCDs reproduce colors accurately without depending on the user being in a fixed position in relation to the screen. Such technology is present in iMacs, Cinema / Thunderbolt Displays, iPads and iPhones 4 and 4S, as well as in Kindles Fire and NOOKs Tablet. Taking the three tablets with IPS screens, DisplayMate tried to find the best one, but failed. She found the worst, however.
Explaining: NOOK and iPad have their qualities and defects, but with the Barnes & Noble gadget in advantage, for having higher pixel density and contrast calibration and gamma better, besides being less reflective. As for the Kindle Firebem, it had problems with the display of gray tones (which, on the good side, can be corrected with a software update) and has the screen with the highest reflectivity of all (irony!).
It is worth noting, however, that the position of the iPad in relation to its rivals could change drastically in 2012, with the introduction of the noisy model Retina and / or one of 7.85 inches.