You were using a 6S? that has to be one of the greatest jumps in phone technology I've heard of
Sure was! My wife is also on a 6s and still holding out. I legit haven't cared about any new iPhone since the 6s until it became clear it was time for a new one.... dropped in water 3x. Changed the battery 2x, once by Apple, one myself. Screen has a bluish tint and blotchy streaks from water damage. Can't see the screen very well or at all in direct sun. Earpiece and speaker volume both really really low. Battery life dismal. Camera looks pretty bad. Water damage probably to blame for a lot of it's current state. The 6s was/is a super solid phone though. In a lot of ways I miss it. I really liked that design, and it took the disaster that was the 6 and made it something really create that has had a lot of longevity for me.
The 15 really is a pleasure to use though. My kids are sort of obsessed with it both being on SE (2nd and 3rd gen). My wife could care less though. She'd use that 6s for ANOTHER 8 years if it would last that long!