This is interesting to hear. I have polarized sunglasses, and often have to take them off to see my phone.
Improved polarizer
Your iPhone goes everywhere you do. And sometimes thats outdoors in the sun. With that in mind, the Retina HD display has an improved polarizer so you get a clearer view when youre wearing sunglasses.
Even if you rotate to landscape?
Ditto. This is a change, but not a great one considering portrait is the main mode.It's actually better in landscape (at least with my glasses). Brighter. Portrait looks good but there is a fairly significant dimming.