Just got my ring... Cant say I'm entirely please. But first thing first... Yes, it works with my Moto X. The ring itself, it seems i got my size a bit wrong and I was expecting it to look like this, but instead I got this.
I didnt bother with the official NFC Unlock app, and just used Moto X's built in unlocking, works just fine. Took me a while to figure out the sweet spot, sometimes still takes a while to trigger it though. Would be nice if the sensitivity/range is greater. Oh, and I've no idea how the ring is built but seems I can only unlock with the black part of the ring, no other spots.
Overall, it's a pretty nifty toy I guess. I've no clue whether I got the wrong colour or the pictures were simply misleading, Signature rings are meant to look like what I received? Anyway, probably too much hassle to get replacement for the right size/colour so I'll just leave it be..