A conversation using a phone on your wrist is anything but private. . . and I hate people who use speaker phones in public. That is what happens even with the Apple Watch. It allows you to handle a quick phone call, but it is not intended for long conversations on your wrist watch. For those, you get out your iPhone and have a private conversation. For this reason alone, those stand alone wrist phones will be a fail. They will make their owners social pariahs.
The battery life in those phone watches is abysmal. . . it takes a lot of power to transmit and receive phone calls. It has to be on continually awaiting an incoming call. That means the case has to be large enough to handle the batteries to supply the power. Time between charges on one of the phone versions is in hours and their specs sheet doesn't say anything about talk time.
The Samsung Gear S wrist phone is 1.66" wide by over 2.3" long by a half inch thick. It weighs 2.36 ounces, not counting the strap. It's heavy, more than half the weight of an iPhone 6 (4.6 ounces). You still need to own an Android phone to download apps to load onto the Gear S.
Fine print on the Gear S says:
Gear S: Requires pairing with a compatible Samsung smartphone (sold separately) with the Samsung Gear app for activation, software updates, app downloads and to route calls, text messages and 3rd party app notifications from smartphone to Gear S.
Oops.
Here's an actual topical question for the thread. (imagine that!)
Let' say you have an iWatch. You answer the call. If you find it's a conversation you need to extend can you pull out your iPhone, and have the watch hand the call off to it? I would imagine it would, as the call actually seems to be processed on the phone and is forwarded to the watch via bluetooth.