i have been using iphone for a year now (sure i have had ios devices all the time, but not using the iphone as my only primary phone).
1) For sure the ui is boring. it cant be customized - moving icons on the screen or putting them inside folders and changing the wallpaper. Thats all. it has been pretty hard to get used to it when i had my android phone running several handy widgets at the same time (i quess around 30) and Zooper was (is) my best friend...
2) Battery life is good. much better than any of my android had/has, but i quess you cant get all in the same package.
3) widget? ehm... yeah. i rarely use them. ackward to access (scroll left, scroll up and down, press here to view more...) and when you finally got something to work, it was locked out in the next ios update.
4) imessage? i dont used it as ios isnt popular here. and i prefer apps that works with differend os's, so it doesnt matter what device im using and i dont need to know about devices the other has.
5) security? a reason i switched to iphone. i must say, that google sucks with its policy. i have only paid apps in android, but it still sucks. if i install the app today with no extra access, it gets an update tomorrow and wants to access to everywehere. E.g. today i install calculator app, with no extra permissions. tomorrow the new version is out and when updating the app, it tells you that the app wants new permissions to access my contacts, read my messages etc. what? an calculator? why? no, i probably dont switch back to android until google does something to its loose policy with apps and privacy.
6) 3d-touch. i tried to get used to it, but i havent found any feature which would make it easier to use 3Dtouch vs. launching the app.
7) live photos. no use. they were fun for couple of days. then i turned it off. also cant be saved to a nas i use.
8) live wallpaper. it is a real gimmmick - who is going to press long the lock screen just to see the backround moving?
9) siri? no. when the iphone is locked the usual answer i get it is "you have to open your iphone at first." and siri doesnt work with atv in my country...
10) sharing/downloading/uploading? a nightmare. you will hang yourself before the sun is down if you dont install Documents5.
11) camera/vid. good - but the software is way too simple. you want to install other apps at once.
12) 100mb limits to download app. eh? i was in an event once and i was supposed to install an app from appstore to get things done. no, i couldnt because the app was over 100mb. wtf? im not sure if it is now removed with ios10 - i truely hope so. if you have two ios devices with you, e.g. iphone and ipad cellular, you can round this restriction easily - using the hotspot.
13) ecosystem. i would rather say egosystem. i dont have any needs to hang myself or boost my ego building my life around a company. i always hear people saying how good it is to work with apple ecosystem, like starting to write something with your ipad and then continue with your laptop etc. or start writing a message with iphone and then grab ipad. who is switching devices between writing a simple message? i wonder how many times, except testing it, people actually do any real work changing between devices. atleast do any other work than reading emails with ipad. i dont, im not going to write or start writing texts with ipad. im not going to use pages with ipad to write anything - if i need pages, i take my macbook. pages in ios have no possibilities to add e.g. equations - again i need my macbook. but i still dont use pages because we use word at work, i should fix everything i write using pages to look good in word.
other than that, airplay works great. i cant say exactly the same with my android tvbox (it usually takes couple of steps), but the android tvbox also let me sharing the screen or airplaying with windows and ios. airdrop between osx and ios works easily.
14) apps? i have same apps on ios/android. both looks the same mostly. there might be some differences, depending on the developer usually, and because of restrictions with os (usually in ios).
15) crashing? both suffers. ios just doesnt tell you that while android openly let you know it. when apps crash in ios, you think that you just closed it. if you check the crashlog, it wasnt you, the app just crashed.
16) os? simple to use, but actually im not sure if the os is simple at all (it just looks simple) and i wonder if it is also the reason why the user has no real access to folders and a possibility to share files because the filesystem is a one big mess(?) e.g. your songs are put on abcd-named folders, each of them, and named same way oddly. if you have access to those folders (e.g. using ibrowse from your computer), you have to browse each of those folders and to listen them to find the specific song. and with every updates, they break something and several updates are needed to fix them.
17) ringtones? yeah, buy a bottle of wine and prepare yourself to follow the 500-steps procedure to make your own ringtone from the song you have.
what else? yeah, im probably not switching back to android phone until google does something to the privacy issues with apps. and the answer is not letting the user to toggle switches on and off, but rather demanding developers to honor peoples privacy and removing those apps that have ridiculous access which apps dont need. no, a calculator app doesnt need to know my bankaccount and ask a permission to write bills.
iphone does all i need from a phone. i can live with it. but ios generally? no, it becomes more complicated to do tasks than using simple functions with a phone.
i have ios and osx, also tvos, but also android and win. and everything just works! no problem to switch back and forth and no needs to build my life around any "ecosystems" and finally realize that i have invested so much money to it that i cant leave it and i have to live with it.
and... this was my personal experience - some other may think differently.