having played with an S3 i can say that the new iPhone, if it does turn out to be a slightly elongated 4S like it appears, just doesn't cut it anymore.
Retina screen is ok, but to my eyes the Samsung Galaxy S2 and S3 screens look far brighter, and colour rich than the iPhone 4S screen, blacks look blacker, colours look brighter and crisper on the Galaxy Screens... that's before you get to the phone feeling better in my hand because its nicely curved and large enough to just sit in my hand.
the iPhone (the 1st gen one) blew the competition (which was Blackberrys, Windows CE mobiles and Symbian Mobiles) out of the water in usability and interface, now, the android phones have caught up, and offer a wider range of phones to suit all hands, usually for free.
The iPhone is, with every iteration, feeling more and more like the "old" phone in the room to me now, no innovation except in adding features by software update (that are then withheld from the older devices purely to force people to upgrade).
Apple need to expand the line, offer people more screen sizes for a start, and, offer the phones at a price that lets the networks offer it for near free, like the android phones (they make enough money of the App store to use it to subsedize the phone) If i can go and pay £32 a month for a Samsung Galaxy S3 with a one of cost of £29 for the phone, or £40 a month for an iPhone + £300+ for the phone, i know which one im going with,