It's difficult to recommend the display compared to the rest of the smartphone world, as there are definitely better screens out there. The iPhone 6 and the iPhone 6 Plus, not to mention the even newer iPhone 6S and iPhone 6S Plus, offer higher resolutions, and larger displays, and the Plus models boast a higher ppi. Whether this is enough for you with the competition being so far ahead is something I'll leave you to work out.
The four-inch size of the screen is good enough though, as while I might be a fan of the larger screen for movies and internet browsing on the Samsung Galaxy S6 or HTC One M9, the iPhone 5S is a good phone for people that hate the idea of being forced to live with a bigger screen they don't want.
It's not perfect though, as despite what Apple would have you believe, the screen is just a tad too large to operate easily with one hand.
With a small amount of shifting you can get the thumb all the way across, but given you have to jiggle the phone in the palm a little bit to do so, it kind of feels redundant.
In terms of the clarity of the iPhone 5S' display, I'd say it's excellent in terms of colour reproduction and general effect, but there are better displays to choose from - the Sony Xperia Z5 is worth looking at, for example.
The sharpness is great, the colour reproduction still industry leading, but the brightness can be a little erratic for some low-contrast movies and isn't big enough for speedy typing. HD movies still look acceptable on the device, but I've seen a much more jaw-dropping effect on rival devices, such as the LG G3 and its successor, the LG G4.
I like that Apple is leading the charge to stop screen sizes going too far in the wrong direction, but there could be something more that's done here.
Even a display with a thinner bezel would have impressed (although scaling apps might have been a problem, with is something Apple is so proud of) but I still think in the face of fierce Android opposition the iPhone 5S display could be better.