To answer the question simple: very good, nearly excellent.
A larger and more comprehensive answer would require breaking down the specs of the two models and explore just how much the iPhone 6 has improved in some major areas. Lets’ go.
Design and Display
Let’s start by saying that the iPhone 6 is a completely redesigned device. For starters, it implements new and modern principles, which translate to a curvier device with round edges. This makes the handset more compact, comfortable and ergonomic. The iPhone 5S, is designed with sharper edges, a flat screen and when put side by side with the iPhone 6, it looks antique. The company still uses same premium building materials, such as glass and aluminum. The iPhone 6 has grown in size, with the display going up to 4.7 inches. It is a major step, considering that the company has long resisted using larger screen than the 4 inch of the iPhone 5S. Besides going up in size, the new iPhone is slimmer, with thickness set at 6.9mm (down from 7.6mm), and still manages to deliver decent weight of just 129 grams. Pixel density stays the same, at 326ppi. The 4.7 inch display in the iPhone 6 uses the same Retina ratio, with the resolution set at 750×1334. The 4 inch display of the iPhone 5S delivers a resolution of 640×1136.
Hardware and Operating System
While the sheer power of the processor is not much increased, up to 1.4 GHz from 1.3 GHz, the chipset is completely new and improved A8 64-bit chipset. The new chipset delivers 30% more speed and power, according to Apple, and is more energy efficient. Both devices have 1GB RAM. The built in memory versions include 16, 32 and 64 GB for the iPhone 5S, and 16 and 64GB versions for the iPhone 6. There is no option for expandable storage in both the devices.
The OS is where the iPhone 6 earns its money. The new iOS 8 is improved in every section. The iPhone 5S can get the upgrade as well, but the iPhone 6 has some features that are not available for older handsets. For starters, it uses NFC technology for mobile paying system. That is the single biggest innovation from Apple in the new handset, one that everyone expects might change the landscape of the mobile paying system worldwide. The company already has several partners such as Visa, and retail markets that are willing to accept payments via Apple’s NFC paying system.
The camera in the iPhone 6 is the same 8-MP sensor used in the iPhone 5S. However, Apple has made some minor tweaks in order to improve the quality. For example, the new lenses are bigger and allow for more light to come in. Additionally, there is a new sensor that focuses pictures faster, and improvements in the A8 chip that solve the problem with shaky hands. Another new feature is the time lapse shooting mode for video recording.
Apple has beefed up the battery a bit, up to 1810 mAh capacity. The iPhone 6 delivers 14 hours of talk time, or 4 more than the iPhone 5S. The battery in the iPhone 5S has a capacity of 1560 mAh.
The price of the iPhone 6 is set at $650 for a SIM free version. Before the launch of the latest iPhone, the iPhone 5S was priced at $500. That price might drop in the following months.