I should carry a big screen around with me? I'm not a professional, it's just a hobby. Yes, if I PLAN to show pictures, I want a bigger screen. If I am just having a conversation with someone, it's nice to pull out the phone and show them. I'd rather they see a 3.5" version of my picture as I processed it on my laptop than a 3.8" version (3:2 format, the 4.8", 16:9 screen does NOT make the picture 4.8") that is WAY over saturated and NOT what I saw when I processed it on my computer.
In this way, even the new "larger" screen on the iPhone 5 will be the same size, as the width isn't changing.
If you want the phone to re-crop your image and show an over saturated 4.8" image, by all means, use the Galaxy S3.