The reviews about the Gear S that said this KILLS THE BATTERY FAST (especially GPS+Cell), I'm guessing you'll need to recharge once to finish the day (unless your use the rest of the day is slight)...
I workout or run in the morning for 1-2hrs total time with the Gear S and battery goes down about 35-40% if I use the both GPS and BT for music. I charge it while I'm showering and it's back to 100% with ease. It's all about understanding the technology. Many of the reviewers clearly do not. Read them too.
Typical use, which doesn't include a long run with the GPS/Cell running is 16h (as reported on review sites). The charging thing also has a propensity to fail (and Samsung dragging its feet on replacing it). The reviews for this thing are not glowing at all BTW (3.5/5 average).
16hrs sounds about right if GPS is on. However, there's no need to leave GPS on unless you're using it without a phone and need GPS. Otherwise, it taps the GPS off your phone when BT connected. Charger wise, people are breaking the top tab. I do agree it's not a great design. My son broke mine when I asked him to get it off the charger. Meh...not a big deal as it doesn't cause anything to "fail" it just requires I charge it with the batter secured to the watch via band of velcro or something. Not ideal, but it doesn't matter to me.
The point is, I won't need a phone either (and who cares about GPS tracking (are you lost?)
You must not be a runner. Health/running apps can track your route, track distance, time, speed, etc. Again, if you're not into running or biking, then you won't need it. In terms of GPS use, it's awesome to use when I'm in the city. Traveling in NYC for example, I can go out, not take my phone and still have a fully functioning GPS and text, email, contacts, schedule, and full phone capability.
Personally I enjoy trying to break free from carrying a physical phone. Helps me focus on other things more and people across from me vs worry about leaving my phone on a bar, in a cab or having to tuck it in pants pocket, etc. I can run errands while at home, leave with just my shorts and a t-shirt and not have to even take my phone because it automatically forwards everything. It even connects to the BT in my car where I can then stream from Milk Music play my songs off it's storage or answer calls seamlessly.
When its unreliable to tell you the speed your going (precision is about 8meter even when you don't have obstruction)) and I value not having a big sweaty hunk on my wrist when I run 1h+.
You clearly don't use one or you'd know the accuracy is spot-on. It's not some 8M off when running. It's also very light in weight. deceivingly so. Much easier than having a phone strapped to my arm or bouncing in my pocket. Again, it's clear you're not as avid a runner so I wouldn't expect you'd know.
The heart monitor on the watch is also not really that good even at rest (as reviews report, let alone when you run).
as reviews report.....

You're funny. Works fine for me and matches my Polar Beat device fairly closely. Problem with the reviews is they likely don't wear it snug as people tend to wear watches more loose than tight which of course isn't going to work well when you're trying to have a sensor make contact with your skin. I do the same as I like a loose fit but when I run, I move it one notch tighter. All in knowing how to use a device.
In the end, no doubt the iWatch with it's apps and great interface will be a huge hit once they put a sim card in it. I'd even likely switch to iOS again if they did that.
I do also think once the masses realize the benefits of even a tethered device in the world of iOS they will take off even faster. IMO they just need to work on the styling a bit. Offer a nice
LG Watch R round style and I think they might win more appeal as well and is one of the best looking ones out there. That would of course be more work for interlace design, etc. and based on typical Apple, I don't see that happening.