Interesting. I made the same jump and noticed a huge increase in speed and decrease in memory pressure (the likelihood that iOS will kill an app I've switched away from). I miss the physical silent mode button though.
The camera button on the 16 seems to have been perfectly engineered to be exactly where I grab my phone. I'm sure I'll get used to it, but in the mean time I have so many blurry photos of desktops and pants to enjoy.