"The iPhone 6 was already a spectacularly great phone. If you’d have to pay an early-termination fee to get the iPhone 6s, it’s probably not worth upgrading to the 6s.
But if you have any older iPhone model, or if you’re paying monthly for one of those “switch phones whenever without penalty” programs, or if you’ve been poised waiting for the right moment to jump into the iPhone parade, then the iPhone 6s might be singing your name. The speed and the 3D Touch features are the meat of the upgrade. The rest is just “s” gravy, but really delicious gravy."