Seems pretty easy to sell it now that it's unlocked. I found several buyers for ~$650-$700 locked, and now that it's unlocked $750-$800 seems to be the going rate. Note that I also have AppleCare+ with it which I probably can't return anymore, so it's really a $925 value. It's easy to sell right now because backordered on Apple's site. Might get harder once they meet demand.
I'm just holding on to it because I really enjoy having both an Android and Apple device right now. Even though I prefer Android overall (and the Nexus 6 is impressive), some things about the iPhone (fast AF, 240fps slow-mo, laminated screen, and generally the sleek form factor) are just really beautiful.