Lots of people keep saying that the differences between the S3 and S4 aren't significant enought to justify the switch or all the hype that Samsung is giving it. Apple does the same thing. There were never many differences in hardware from one iPhone to the next. Most of their differences were with software. Android adds new software updates independantly and they are always significant. Apple took the idea of a cell phone that can play music and text from other companys, dumbed the process down for the average apple user and put a shiney polish on it. Samsung took the iPhone, put an open sourse OS on it and fixed just about ever iPhone user complaint (removable batteries, removable storage, easier customization, load music without needing special software like iTunes). Apple is now receiving the same medicine it has been giving out for decades. If you upgrade your phone every 18-24 months and your upgrade is due about now, the S4 is a HUGE upgrade over anything you had 18-24 months ago. If you just got an iPhone or S3 back in Jan or Feb.... well sucks to be you. Have fun waiting. At least you can say that your upgrade 18-24 months from now will likely kick the poo out of the current iPhone or S4.
Bottom Line. Well Done Samsung. Mobile users spoke and you listened.