Numbers that make all the manufacturers jealous.
5S is a great upgrade from 4/4S. Is it ideal screensize, probably not, that's coming with the 6.
But having way faster hardware, 64 bit processor, everything is substantially faster, better camera and flash. There's plenty of reasons to upgrade.
I will be, and so will 2 other of my colleagues (Software Architect and Software Developer [Java]). and other family members will be upgrading.
To all those who think people with iPhones don't know technology, products, don't do research that's complete B.S.
I know many people like myself well versed in computer technologies either from a software or hardware level, CS degrees who simply have a long list of reasons to prefer iPhones over Android phones and we don't really need to justify it to anyone else but we can.
Our marginal utility for an iPhone is higher than a S4 or Note 2/3.