Apple really pulled out all the stops with this update. For one, the megapixel and processor boost then the 3D touch. Count me in. If you don't believe me, take a look at the photos from the iPhone 6s! Also, yes, if you want Optical Stabilzation, you'll have to opt in for the 6s Plus. Now if I could decide which case to get.
note: I'm still using an iPhone 5 at the moment so an upgrade was due a year ago