I upgraded from the 6 to the 6S and I like the latest and greatest so I will do so every year however in terms of upgrade its not been great. Touch ID is faster so I now use that only 2 generations on as it never worked before. 3D Touch no need for this. 12mp and 4K not been on any holidays yet so never required yet. Selfie flash never use this. Live Photos used a few times but now turned it off as it messes my photos up. Most of the S features are good to show off but you never use them much until a few generations later. E.g 4K may be popular once we all have 4K TVs and a larger entry model storage. The 3D Touch is quite flawed as when you want to delete an app it thinks you are using force touch. I never use Apple Pay either. Processor wise the 6 was never that slow and I am sure it's still decent on ios9. I feel this way with most S models. I've read 3D Touch is not poplar with everybody anyway.