At least for Series 2 this isn't that much of an issue any more: despite tracking a 2 hour workout every day, the battery easily lasts through the day and the night. And it recharges fully while I'm showering on the next day.
I could easily use the watch for sleep tracking, but the SDK is a bit limited for 3rd party apps to be able to automatically start and stop tracking.
I hope Apple will either improve the SDK or add a built-in sleep tracker and alarm feature as described by OP (though in my case the point is moot as I have a very efficient fur-based alarm clock that will claw my face on the first sign of daylight in order to be fed)
I agree; I charge it while I'm in the shower and so does everybody I know who actually uses their Apple watch (which means, about 15% of those people I know who bought one).
The battery (in the second version of the product) now lasts long enough to make that work — except sometimes on the weekend when I might go a day without a shower.
I also want the smart sleep tracking app badly. The reason I bought this crappy watch was solely for the vibration-on-wrist when you have to make a turn when using navigation.
Unfortunately, that iOS feature is horribly broken — it automatically switches to "car mode" when you go faster than a brisk walk, which means it doesn't work for navigating on a bicycle, skateboard, foot scooter, or even just running.
So the device has very little utility for me as it stands — but a sleep-cycle-aware, vibrate-only alarm clock would make it worth the purchase price for me.
And Apple (since I know you clearly must lurk on every hacker news thread waiting for unsolicited advice from strangers on how to fix your lame products): fixing the stupid "automatically switch to car mode" misfeature would also make the watch worth its price to me.
I could easily use the watch for sleep tracking, but the SDK is a bit limited for 3rd party apps to be able to automatically start and stop tracking.
I hope Apple will either improve the SDK or add a built-in sleep tracker and alarm feature as described by OP (though in my case the point is moot as I have a very efficient fur-based alarm clock that will claw my face on the first sign of daylight in order to be fed)