Currently using a Note 2 and will be upgrading to a Note 3. 5s is personally a downgrade for me.
I wouldn't switch back personally. The battery on the iPhone is much shorter and the screen is just too small especially coming from a note. You'll also miss the dedicated back button.
I used to be hardcore Apple user; switched to Android a couple of years ago (Nexus One). I wonder if anyone has recently gone from something like the Note 2 back to an iPhone? How is the experience? What do you miss from Android?