My only cel phones so far have been iphones, and I've never given switching any seriously thought, I'm not sure I'm even a phablet kind of guy, but I tried a note 4 today at an AT&T store. The only thing I cared about was seeing how sketching would feel on it. I don't know about the rest of the phone but I am jealous of that feature alone. It could replace my sketchpad in many ways.
Of course, given the option I'd go for a full on cintiq instead, but those are still ridiculously pricey for me.
I don't think I could give up the selection we have on the app store though. Maybe if I had an ipad, so I could have the best of both worlds.