It's very minor if you have a 6s, but then again, most (not all) iphone generations have been pretty incremental from one to the next. The prior year's model is always quite compelling, even when the new one comes out. What's disappointing people, I think, is that this is the second consecutive very modest update.
For my part, I went from a 6 to a SE a few months ago and will keep the SE until fall 2017. Kinda an 18 month upgrade cycle due to the SE coming in the spring. If I still had a 6, I'd probably upgrade but not feel great about it.
To each his own, but I cannot fathom how these updates could be seen as "huge." The new colors are black... and black. I'm glad we have black iPhones again, but honestly, we're getting excited about a black phone now?
Waterproof may be important to some, but I've never once gotten an iphone wet. Not sure why this one matters more than a tiny bit for accident protection.
A camera upgrade is great, but the camera has been upgraded literally every year except iphone --> iphone 3G. That and a processor bump is the absolute bare minimum we can expect.
New home button that is getting absolutely shredded in the early reviews. Even if it turns out to be an upgrade, how much does that really matter to your experience? Was the old home button holding us back?