iPhone 5S Teardown Shows Moderately Repairable, Elegant Design
Right off the bat, it's evident that Apple hasn't changed its stance with the DIY crowd. The iPhone 5S still sports pentalobe screws, meaning you need a special (and hard to find) type of screwdriver, which of course you can find at places like Amazon. Adding a new twist, however, is the fact that there's a Gold iPhone 5S, and at this time, iFixIt doesn't have gold colored replacement screws.

Source: iFixIt
Another new twist is the presence of a fingerprint scanner. That means when opening the iPhone 5S, you'll want to gently use a spudger to carefully pry it open, as there's a cable at the bottom connecting the Touch ID sensor in the home button to the Lightning port assembly.
"This adds a small element of danger to disassembly, as pulling too hard on the suction cup could cause accidental damage to the cable," iFixIt notes in its teardown.

Source: iFixIt
When it was over, iFixIt determined the iPhone 5S should score a 6 out of 10 in terms of repairability, where the higher score, the easier it is to service and take apart. The iPhone 5S lost points because the battery no longer has a convenient pull tab and has a lot more adhesive than before, the fingerprint scanner cable could be easily ripped out of its socket if you're not careful, there are still pentalobe screws, and the front glass, digitizer, and LCD are all one piece, which could increase the cost of repair.
On the plus side, the display assembly is the first component out of the phone, which simplifies screen replacements. iFixIt also gave the iPhone 5S kudos for the battery still being easy to access even though it's not supposed to be user replaceable.