I only owned iPhones until last year when I switched to the S8+. I bought it right after Apple announced the price of the iPhone X. Too me, $1000 is too much for a phone. The first weeks with the S8+ were a bit difficult, missed a few things from the IOS. But as time went by, I got used to it and today I'm really happy with the phone. It's just a bit faster than my last iPhone (6S) but it's perfectly fine. Don't feel the need for a faster phone. It's also the most beautiful phone I've ever seen, hands-down. The ecosystem thing was the easy part: I've never used iMessages (I don't live in the US) and I've never really liked iTunes nor Notes (I used an app called Phonograph that's 10 times better than iTunes and Simplenote - simple, easy, fast, free).
Will I ever buy an iPhone again? Maybe, but first I need to see an iPhone with a better wifi chip (the intel chip is a deal breaker for me - I travel a lot and always need great 3g/4g speeds to communicate with my clients) and more reasonable prices.
Also, I really don't feel the need to upgrade my phone. It has everything I need and it's a pleasure to use. So I got the feeling I'll keep this phone for another 2 or 3 years (or until it dies on me or the battery goes bad).