Watch arrived smartly boxed. Opened, charged to 100%. The charger magnetically couples to the back of the watch. Charging time is fairly quick. There are 2 tiny pins that serve as connectors. I would think these could be somewhat fragile and should be treated with care.
Next, downloaded Google Wear OS. Took a few "do overs" to get app to pair with watch. Once that was accomplished, started in on customizing settings and watch faces. The 416 X 416, 44MM AMOLED display is awesome - sharp, bright, colorful and excellent contrast. The processor is a Qualcomm® Snapdragon™ Wear 4100. Along with 1Gb ram and, 8GB Storage the watch has a snappy performance and plenty of storage for additional apps.
For sensors, it has accelerometer, altimeter, ambient light, compass, gyroscope, heart Rate, SPO2, along with a number of exercise metrics. Keep in mind, this is not a medical device, so readings may be inaccurate. I found it measured a few "steps" while sitting down....
Notifications include apps, text messages, receive and make calls, sync calendar and get reminders, etc. For connectivity, there is blue tooth, wi-fi, NFC.
Has built in speaker, mic, and vibrate function. The band is a 22mm quick connect, and easily interchangeable. With all the excellent capabilities of the watch, why the lower rating you may ask....
There are 2 things I feel detract from a 5 star rating. One, Wear OS is a bit dated, and should be upgraded to have a better user interface. And next - and most importantly - I find it disappointing that such an excellent watch has such a mediocre battery life. It looks like this will need to be charged daily. This certainly makes the sleep tracking difficult or impossible due to battery life.
I would sum up with this is an excellent watch, if you can work with Wear OS, and deal with daily charging....