The iPhone 6, its A8 processor, and its M8 processor help to provide fast and fluid performance. iOS 8.4 runs very smoothly on the iPhone 6. There are also some other things that these features can do, things that you might not have been aware of.
Thanks to the M8 co-processor, your iPhone 6 can now actively track incoming data from its various sensors (accelerometer, compass, gyroscope) including the device's barometer. The barometer helps with measuring stairs and hill climbs. That's going to be essential for those of you that are big into fitness.
The iOS 8 update and Apple Watch have ushered in a new era of fitness at Apple and we're confident that we'll see new iOS features and improvements come to the iPhone 6 in future updates.