Couldn't have said it better myself. I did a hard reset about a month ago and it solved the problem; the battery started draining like a sieve this week, did a hard reset and it hasn't done anything to resolve the issue, just like everyone else has posted. I'm really beginning to doubt that anyone at Samsung even reads these posts and realizes how frustrated their customers are.
The main reason of this issue is the app and 3rd party watch faces. Please just reset your watch and make sure fully carged. Now use normally without any third party application. I hope your problem will be solved.
This is a new issue not related to watch faces. My battery in the last couple of days has gone from 100% to 0 in around 12 hours or less. No new watch faces or updates in that time though I have noticed higher data usage on the Samsung accessory service app, 160mb in a 6 hour period in the background.