This phone is really awesome. It is currently the fastest smartphone in the world.
Some of its features are: -
2 gb ddr3 ram which makes it even better
12 mp rear camera it can snap really amazing photos and ca record 4k videos.
Better touch id
Better screen
3d touch enhanced
Faster processor
Full metal body
It comes loaded with a A9 chipset which is very fast.
One of the major changes is SIRI
Now you can say hey siri anytime and siri is there to help you.
Therefore you should buy this smartphone