You know.... Having come from Android prior to me getting the 6s Plus, I was already used to phones starting to not run great after a couple updates. Not to mention, no matter what Android phone I had (HTC Incredible, Galaxy SIII, Galaxy Note 4, etc...), none of them offered the battery life of IOS. I really like Android, but I've also learned to like IOS. I like it enough that it is doubtful I'll bother going back to Android. (Well, if Apple releases Messages for Android, I'd be tempted to go stand in line for a Galaxy Note 9

) I love me some timely updates, not having to worry about battery drain, and the other headaches Android can give. Android can do a lot more than IOS (IMO) but I like the simplicity on this side of the fence. It does everything I need it to do. You're lucky if your Android phone got full support for even two years.
I got my 6s Plus mid cycle... like in April or May. It still runs terrific. The battery thing did bother me though. I like many others though think bothering to have a battery changed is not worth it generally. A phone should last about two years and then it's time to move on and get the latest and greatest. I considered the iPhone X. I'm use to automatically getting a new phone around every 20-24 months. Was online at release and had one in my cart, but to be honest.... I like my 6s Plus. I'd love a larger screen... 6" or more. I also wasn't crazy about having to use my face to unlock... but I'm sure the fingerprint will be going away all together on IOS. I figure I may as well hang onto it a little longer.
Then, the battery thing came out. I was disappointed. I don't buy that it was for user experience completely. They don't have the best track record with speaking the truth. (Antenna Gate anyone??? Really, holding it wrong???) Still, I think this is admirable to offer the discount and come up with some sort of app to let us know when our phones are being crippled. I don't expect a phone to last me four or five years (nor would I really want it to), but I know they are expensive for some people and it sucks to be on an older device because that is all they can afford. I think a 29 dollar battery is a good start.
That being said, I already ran a bunch of tests to make sure my phone wasn't being slowed down and that my battery is still in excellent condition. I only charge it once every four days or so, so I wasn't surprised to see I don't have that much degradation. (I learned the hard way with Samsung devices that the battery would die at an inconvenient time and they had "discontinued the battery"... eye roll. That was the day I was in Verizon Wireless and said, Give me an iPhone... I'm over this sh*t.) Ha!