Well, think about it this way. It's all proprietary. You need the adapter to use old 3.5mm headphones. Sure the iPhone 7 comes with it, but if you lose it (and I believe most will), it'll cost you $9 to replace. As well, if you want to use the adapter so you can use your current 3.5mm headphone (instead going out to by $150+ wireless headsets), you CAN'T charge your phone at the same time. Your stuck with one or the other. Hardly innovative. And the headsets that come with the iPhones suck! Terrible sound, and doesn't sit well in the ear. To get a nice deep base, you have literally have to jam them in your ear (to make a seal), but they don't stay in. I can't see the airpods being different, other than it's wireless and $150.
The 6S has already been tested (independently. check youtube) to be water proof/resistent. So the "water resistent" sell, is moot.
Except for the camera, there really isn't anything innovative and new on the iPhone 7. I'm sure, as with all other initial launches of new phones, there will be kinks. Which they will fix, and improve upon on the 7S. So if I decide to upgrade from my 6S, I'd wait till the 7S.
They also got rid of the 64GB model and 16GB model, with 32GB, 128GB, and 256GB. I can understand the 16GB, that's way to small. Considering the file sizes of pics and videos on the 6S. IMO, 64GB would be my choice. Not too big, not too small. 32GB would be bare minimum for me, and I'd find myself having to constantly backup and delete photos and video on my phone to make room for new ones. Or better yet, why doesn't Apple just build a micro SD slot on their phones. Oh, ya. It's called proprietary.
The main reason why I've stuck with the iPhone for so long, is because for me, it's always had the best camera. Still does. But even this isn't enough for me to even consider upgrading. The processor speed is also important to me. But considering the 6S is almost twice as fast as the 6, that means the 7 isn't that much faster than the 6S. At least not as considerable as it is against the 6.
My biggest take away, is removing the 3.5mm input. There isn't any reason for it, except to set a new trend. A trend most really don't like.