People seriously considering not upgrading because this is not a design overhaul?
Guess what, I don't mind, as much as I don't mind Mac's design being the same for years if the design is good. Granted 6 and 6s design was one of the worst of the iPhone lineup, but I actually like the tweaks they made on the iPhone 7.
The camera protrudes but it does not feel constrained anymore between the antenna bands and, most importantly, follows the corner radius of the iphone structure. Once you realize that this does not happen in the 6 / 6s you'll get some serious OCD about it, trust me. The antenna bands got reduced as well.
As long as Apple introduces more performance, better battery life, better camera, some cool new features design leaks can't leak, and of course, a reasonable way to use headphones and earplugs, I would call it a good upgrade.