If you thought polka dots were a thing of the 80's, you were mistaken.
Some iPhone users have had the fortune of receiving units that have a screen issue that manifests itself with little white dots in a checkered pattern over the screen.
Forum users have identified that affected units have display model number 7455232, although not all models with this screen are affected. The issue appears during boot process, which may suggest a software driver issue.
Though not all 7-series display models have the issue, it has also been noticed that the models have more contrast and less brightness than 5-series display models. A comparison picture from our forums is given below (7-series on left, 5-series on right).