Yes, I'm running an AT&T Sim Card, thus it functions stand alone when I'm out and about with my phone resting at home
Stand alone function is the main reason I bought this one. For the longest time I've been intrigued about the likes of the Moto 360 and others, but with them needing to be tethered all the time, I saw little value in them. I mean it's true that I'm around my phone a lot but the occasions where I need it to work when I'm not, the Gear S is great.
I'm sure the Apple version will be cool and likely be as integrated and as smooth as I can expect, but even that isn't deemed to be a stand alone unit, thus of no real value to me.