Thanks to the iPhone 6's support for VoLTE (Voice Over LTE), you can enjoy simultaneous voice and data. This is an extremely important feature and one that isn't available on all versions of the iPhone, not even the iPhone 5s.
This is a feature that you're going to be using often because it allows you to do things like talk to your spouse and give them directions to your location at the same time. On some phones, you can only do one or the other. It's a pain to say the least.
Like Touch ID, this is another feature that will work its way into your daily routine. And like Touch ID, it's a feature that you'll never want to be without again.