I've had a good experience switching to the iPhone. Mostly positive and I don't see myself switching back.
For something that has its roots in a music player, it's a surprisingly bad music player.
I'd bail immediately if it wasn't for imessage. When Apple gets around to ruining that, I'll try something else.
But Siri is bad. Really bad. It doesn't understand me, it does things I don't want it to do, and it's very inflexible.
Siri was usable on IOS6, and has gotten worse with every release since then. I don't use it at all any more, and would turn it off except Apple loves to tie its crap in with things you need, like voice recognition.
Apple peaked at IOS6.