4.7" screen with a 16:9 aspect ratio like the HTC One X is the perfect size. It has the width of a 4.3" screen making it easy to operate with one hand and still gives you heaps of screen real estate.
Its far superior to the 16:10 4.8" screen on the Galaxy S3 which feels every bit as enormous as it sounds despite being only slightly larger than the HTC.
That's the problem for the rest of us who want a larger iPhone. Not everyone can afford both an iPhone and iPad. Also the iPhone is the one device that I take almost everywhere with me so I want the larger screen to make it more enjoyable to use doing other things besides making phone calls. Some of us do want an in between device. 4.3" is the largest I would want the iPhone to go though.
There is an easy solution to this. Apple has 2 variants in almost every segment in which it competes.
Desktops: iMac/Mac Pro.
Portables: MacBook Air/MacBook Pro.
Touch iPod: Touch/Nano
Classic iPod: Classic/Shuffle
iPad - iPad and soon to be released iPad Mini.
So why not the iPhone. It actually makes zero business sense for Apple to have one model competing against 3 flagship models from each of its key rivals in Samsung/HTC/Motorola, Nokia and Sony.
They should expand and market their iOS devices as follows:
iPad: 7" iPad and 10" iPad Pro
iPhone: 4" iPhone and 4.7" iPhone Pro