I've tried dozens of smart watches and even regular watches before smart watches existed. I've never before encountered a band that was simultaneously so easy to put on and remove, and so comfortable while wearing it. It doesn't chafe my skin, cause itching/peeling, or have problems with fitting either too loose or too tight like nearly every other watch does. It also doesn't pull my arm hairs (I am a man and my forearms are hairy) like most other watch bands do.
Even if all it did was keep time, this would be worth 5 stars on its own. But it turns out that the Apple Watch is useful for far more than keeping time. I have the cellular model, so I always have an emergency phone call on my wrist, even if I lose my phone. It even gives me an extra sense of security, because if someone manages to steal my phone or attempt to rob me, if I manage to get away from them before they take my watch, I can call emergency services while I'm fleeing. At minimum it will cause them to dispatch a police car as they will be able to geolocate the watch using GPS and know exactly where I am. It will also alert my emergency contact that I set up on my iPhone.
So far it gets so many points for being a security device of sorts as well as keeping time very comfortably. But I also get email and SMS notifications to my watch, and when I turn on "prominent notifications", the alerts I choose to have on are powerful enough to wake me from sleep. So people can wake me up with a text instead of actually calling me. This is great for taking a quick nap mid-day (off the clock, of course) while employed -- if someone needs me, they can send me an email and I'll wake up and read it, and I won't be out of pocket for any amount of time.
It's also a very smart watch for buying gas, convenient entry to movie theaters, tracking my physical activity with Weight Watchers, and so many things I discover every day. Out of all the Apple products I've ever owned, I actually believe that my Watch Series 3 is the most useful one by a significant margin. And that's saying something, because I really do love my iPhone.
It's really a bit funny to me that the smaller my Apple devices get, the more integral they are to my life. I can live without my Macbook, no problem. I don't use my Apple TV too terribly often, either. My iPad's usage is very situational. I'm never without my iPhone, but it's still a bit less convenient to whip out my phone for many things that I can just do on my watch, including taking phone calls and responding to SMS.
I also tried the competition - the Samsung Gear S3 - and wasn't impressed. The Apple Watch is way more comfortable to wear and has more integration with apps and services I use. I would give this watch 10 stars if I could - I've never consistently gotten more value out of a product before than I do with my Apple Watch.