I'm in the same boat (first time on iOS).
This shyt is awesome for me. It covers all of my problems with my past few phones (great battery, camera, Bluetooth works with my car, etc.). I like the interface way better than Android.
Only dislikes are the search isn't as good as Google (obviously), the keyboard isn't as good as the Google one with letter swiping (I have a lot more typos–haven't tried any third party ones yet) and I can't download straight to my phone.
I don't download a lot and am
really meticulous about my file tags and naming, so I go through my computer first 99% of the time. My only holdover is a show that I listen to that isn't podcast capable yet. I used to download the episodes and tag/archive them, then transfer them to my Android phones, but I have been lazy lately. I have been just grabbing the latest episode on the way to work straight from my phone. Now I'll have to go back to my old way of taking two minutes to grab/tag the episodes and put them on my phone before work. Supposedly they're adding podcast support soon, so this should be temporary.
Otherwise, I don't think I'll really have problems. I felt like
immediately after using the 6s+ and don't have any regrets about switching. I just have to get used to how things are done. I have a Mac and an iPad so I don't think it'll be hard though.