What will be interesting is how function the watch is without any other iOS products (if at all).
Actually, if it will function with only Apple devices that makes it very unlikely they would ever reach 10% of the watch market.
As with the iPod where there were far more Windows PC users than Mac users. That is even far more true for watches. Nonsmartphone + non-iOSsmartphone users are
billions more than iOSdevice users.
If Apple caps this just to their own devices they will never get anywhere near 10% of the watch market.
Another thing I'd be interested in is ultimately how much battery drain it would cause if/when paired with an iOS device.
Depends upon how much it is used. Bluetooth 4.0 is quite low powered if not sending any data. If constantly streaming data then it will be more. ( I suspect this is part of the Pebble problem with users and shorter lifetimes).
Also likely to be interesting when 500 of these are brought into the same room and they are all periodically chirping away with connection-status-heartbeat updates.
Compared to a highly focused watch the battery life is going to be horrible. Days as opposed to order of magnitudes longer amounts of time.
Similarly Apple's sealed battery policy. What happens when the battery needs to be replaced? Toss the whole watch?
Unpaired I doubt this device will do anything value added ( for the price paid ) at all.
Would actively using a watch tethered to a phone (if that's how it's going to work) cut battery life significantly?
Depends upon what doing. If the watch is prompting the phone to drag down data then have both radios , bluetooth and wifi/celluar, going at the same time.
Nominal standby mode with the screen displaying time wouln't not do much. Periodically the watch and phone make sure they can still contact each other then the radio mostly goes back to sleep. Shorter but not significantly shorter.