The Gear S has a 3G radio in it, so it can actually operate without a tethered phone giving it network access. This cuts battery life significantly of course, but as I was speculating on Twitter, smartwatches might be able to get away with ‘only’ one-day battery.
I like the conceptual design of this watch as well. My hypothetical iWatch is basically a band that has an integrated — seamless — curved display. The Gear S’s face is not too far off what I imagine. The main difference here is that the screen is still separated from the band — I think the iWatch would be made such that it look like all one part, with the screen inline to the body.