After over a month and a half using the Gear S as my only phone (or should I say trying too during heavy use needs?), I have come to like certain "wrist" abilities and others not so much. Getting notifications is the real standout feature of having a device on my wrist without having to pull a cell phone out of my pocket. Receiving and sending text message is where the Gear S shines for me, but knowing who's calling or texting (and viewing the text) is the really great thing. It gives you the ability to screen calls and read texts without the hassle of pulling out a phone. Although I never setup and used calendar notifications of any kind, I can see how that would be wonderful too.
Talking on your wrist is a nice feature to have, but not all that great for your "only" talking phone. Of course that is not what the Gear S is designed for, but it is how I hoped to use it myself, because I don't like carrying a cell phone in my pocket. It's heaviness on my wrist is noticable too and I wish it was lighter. Finally, even charging it every two days seems like a pain to me. I did't think this would be an issue, but it's getting old already. I find that week long battery life best suits me, although very difficult to achieve with just about any device. The health features aren't something I have ever had an interest in.
I started life without a cell phone, just a watch and wallet. When I added the cell phone to my pocket, I eliminated the watch. With the Gear S I put a bigger and heavier watch back on my wrist and eliminated the cell phone in my pocket, but still carried a wallet. Because of the mediocre wrist talking experience (as my "only" phone), I find it best to actually have a real cell phone handy, but still don't want to have to pull the phone out of my pocket to check the time and get notifications. So the next step for me may be to combine my wallet and phone, and go to a smaller and lighter weight device for time and notifications on my wrist. That might be what many manufacturers researching and designing these new devices already found out.
Because I have always liked the smaller and easier to pocket cell phone form factor (4.5"-4.7" screen), I'm seriously considering moving to the Sony Xperia Z3 Compact in a wallet case with a much lighter Sony Smartband Talk on my wrist for notifications (pictured below).
This will get me into the current OS and top end cell phone specifications without increasing the size of my old Samsung Galalxy S DUOS form factor, plus allow full featured connection to the myriad of new wrist devices available and coming. It's battery life is top tier! Waterproofing is a nice touch too.
I also like the Samsung Galaxy Alpha size and look, but it's not as full featured as the Z3 Compact. Battery life isn't nearly as great either. The big advantage of the Alpha is its' ability to connect to the Gear S and Gear Fit properly.
I haven't made a decision yet. Might wait for the Samsung Galaxy S6 Mini and new Alpha phones to be announced before pulling the tigger for another upgrade change...
Does anyone know of a better wrist device for getting notifications (who is calling, texting and calendar reminders) and the ability to take a call when/if you want to? Health features are not a concern for me and neither is the ability to play music currently; otherwise I'd be considering the Sony Smartwatch over the Smartband Talk.