I came from an iPhone 6 Plus which I got at launch many years ago. I switched to a Samsung S7 Edge but it got so slow and unreliable after a few years I pulled the 6 Plus out of a drawer and have used it for the past 6 months. The battery was fried and apps were slowly but surely going unsupported as it aged, but it was still very usable.
Going to the iPhone 13 Pro I'm pretty blown away. The screen, the speed of every action, the unbelievable battery life, the cameras, etc. It's heavy but feels like a solid brick in the hand whereas the 6 Plus was paper thin outside of a case and felt easily breakable. The weight is not an issue.
iOS 15 feels way more complicated and probably a bit bloated as Apple throws every feature they can into it, resulting in an overload of messaging from the OS about this and that feature. I think that will subside as I get the phone set up how I want it.
My wife is also now (begrudgingly) using a 13 Pro from a Samsung S7 and it's still to be seen if she stops complaining about iOS - she would rather have another Samsung but the BOGO ($800 off at T-Mo) deal on the Apple was too good. She did remark on the amazing battery life - she used it all weekend without a charge (light user, heavy photographer). I'm hoping she'll come around. I tried Samsung for a few years so it's her turn anyway, but if she hates it we'll get another Samsung for her.
I'm not crazy about face id. It's works perfectly in ideal circumstances but with sunglasses or a mask or in the dark it doesn't work, requiring a two-handed passcode entry. The fingerprint unlock could be done with one hand all the time. Under screen fingerprint sensor will be the best solution when it's perfected.