Its only drawback is its use of Samsung’s own Tizen OS. Tizen is a custom OS that’s based on Linux. On paper it’s pretty good, letting you pair the Gear S2 with any Android smartphone, not just Samsung Galaxy phones. But it’s nowhere near as developed as Wear OS, which itself isn’t perfect. There aren’t nearly as many apps available as the Wear OS app store, but the core functionality is at least present from what is available.
The problem is that to monitor your sleeping patterns, a valuable feature most of these new smartwatches support, the watch needs to be on your wrist. So leaving your watch charging overnight while you slumber isn’t going to work. But smartwatches have small batteries compared to smartphones, so should only take 2 - 4 hours to fully charge, depending on the model.
A smart watch is nice to have and it can be a neat buffer when deciding if you want to answer an incoming call or let it go to voicemail. Smart watches with apps for fitness and travel are also a lot more convenient in some cases than having your smartphone. However, if you prefer to use your iPhone for these and other activities, you probably won’t get much more out of a smart watch.
The top smartwatches that debuted at the 2017 Consumer Electronics Show included the Casio WSD-F20, Misfit Wearables Vapor and the Garmin Fenix 5 series. Apple released on September 22, 2017 their Apple Watch Series 3 model which offers built in LTE cellular connectivity allowing phone calls, messaging and data without relying on a nearby smartphone connection. 
If you’re into premium smartwatches, the Montblanc Summit is the latest option hitting watch shops around the world. Out of the box, it runs atop Android Wear 2.0 with the standard specifications — Snapdragon Wear 2100, 512mb of RAM, and 4GB of storage. There’s no NFC or LTE on board, but the watch does feature a heart rate sensor and premium materials.
Our top pick for most people is the Apple Watch Series 4 with GPS (starting at $399), which has a huge display, ultra-fast processor, Raise to Speak Siri, fall detection and a built-in electrical heart rate sensor for taking on-the-go electrocardiograms. It also runs watchOS 5, which makes the watch even more useful with automatic workout-tracking, offline podcast playback and a Walkie-Talkie voice chat feature.