2x processor speed, better battery life, the move to a f.22 aperature lens(f.24 in iphone 5 and 4s right now) 10 megapixel camera. NFC, same looking phone as the iPhone 5 but more durable(stronger anodization/stronger aluminum?)
And I think in iOS 7 it will be a overhaul of the UI. I think in terms of look and it could be one of the biggest iOS updates ever. I think what i listed is what exactly will be in the next iPhone.