I'm one of the many who have had problems with their new 5S. I'm actually on my second 5S, with another replacement scheduled to arrive tomorrow.
That said, I still love the 5S.
I'm coming from a 5, so, honestly, the differences are very niche. Those that care about the specific differences between the 5 and the 5S will care a lot. Those that don't probably won't notice much of a difference at all.
For the everyday user, I doubt they'd notice much of a difference at all, aside from the thumbprint scanner.
For someone who wants to squeeze out every last possible bit of speed from their mobile device, the difference is somewhat substantial. Apps that have been designed to take better advantage of what the new processor in the 5S has to offer are definitely much faster. Safari is faster. Switching between apps is generally faster overall. Mail is faster. The 5 certainly wasn't/isn't slow. But the 5S is markedly faster when comparing processor-intensive performance across the two devices.
The battery lasts longer in the 5S than it did on my 5. Not by a whole lot, but definitely some improvement. I'm not sure if this is because the 5S has a better battery or if the capacity of the battery from my 5 had reduced over the year that I had it. Regardless, I can use my 5S longer than I could use my 5 when I passed it down.
The fingerprint scanner is both a convenience and an inconvenience for me. I was never the type to have a password on my iPhone, so the fingerprint scanner adds a few moments to the unlocking process that I'm not accustomed to (press and hold on the finger print scanner for up to 1 sec, versus press and swipe and be in the phone in half a second). However, the fingerprint scanner is nice for apps that have been designed to use it, like the "Find My Friends" app and the App Store. It's nice to press your finger on the device to log into apps rather than typing in a password. As more apps begin to incorporated his feature, I think it'll become more of a convenience than an inconvenience.
The improved camera is noticeable. The wider lens of the 5S can certainly capture a larger area than on the 5. The burst shooting is a nice addition. The dual flash does make flash photos warmer than on the 5. Theses are all important for someone who uses their iphone as their primary camera, which I definitely do.
The problem I'm having has been the same on both 5S handsets I've had so far. I won't hijack this topic by going into detail, other than to say there's a number of 5S with a defect in the screen that people with good eyesight can see clearly, while other people can't see a difference at all. I happen to be someone who can see it, and it almost gives me a headache to look at. Thankfully, and as usual, Apple is quick to correct a mistake and offer replacements until I win the defect-free lottery.
