A quality test analysis of the displays on the two hottest smartphones of the year gives an edge to the 4 inch screen on the Apple iPhone 5 over the 4.8 inch display on the Samsung Galaxy S III. The analysis was done by DisplayMate which says that the reason that the iPhone screen is better has to do with the 20 year refinement of the IPS LCD screen used by Apple as opposed to the OLED display, developed in-house by Samsung.
The extensive report (which can be fetched by clicking on the source link) gives the Apple iPhone 5 kudos for having the highest Contrast Rating for High Ambient Light score on any mobile device DisplayMate has ever tested. Of course, the subject of the Pentile Display on the Samsung Galaxy S III came up and the testing showed that power limits inherent with OLED screens make the display on the Samsung Galaxy S III half as bright as the one on the Apple iPhone 5.
DisplayMate says that when it comes to the Color Gamut and Color Accuracy, Apple has made a strong effort in making colors very accurate on the iPhone. On the other hand, DisplayMate chides Samsung for not bothering to calibrate the Color Gamut on its OLED screens, leading to wildly inaccurate color representation includsing over saturation of colors which is a standard on AMOLED screens.
Comparing the Apple iPhones 5 and 4, and the Samsung Galaxy S III