Summary
The manual (pdf) is comprehensive and describes the non-WearOS functionality well. r/WearOS covers the WearOS side - check the sidebar too. It is also worth noting that current watches tend to use identical hardware (same qualcomm chipset, same screen resolution, same RAM, same storage etc) although extras like microphones, speakers, NFC differ.
Starting point
I've used Casio digital watches for as long as I can remember. Because they are water resistant, the watch can go anywhere I do, and I never take them off. My favourite over the last decade has been the Solar Atomic models. Solar means I never need to change the battery, and "atomic" means picking up the radio time signals that came from an atomic clock.
Smartwatch?
Watches provide two conveniences for me - it is always there, and I can look at it very quickly. Phones are in chargers, pockets, etc and take longer to extract and navigate to what you wanted to see.
Needing to be familiar with smartwatches, and to do development work I naturally picked the Casio offering which is upper mid-range in pricing.
First Time User Experience (software)
The FTUE is terrible. Android Wear WearOS watches are not mature yet, and require a lot of compromise to keep within available battery, cpu and software functionality. It feels a lot like being given a decade old phone and told to make it work now.
Simultaneously the watch will be doing system updates, installing or updating apps, and have some tutorial overlay you can't just dismiss. All the while you are learning the compromises you'll have to make.
To be clear - it is sluggish. There will be 5 seconds between taps and resulting actions. The screen will go black for several seconds while apps launch. You are never certain if touches or button presses registered, and often end up doubling them which makes things worse. I also found the onscreen keyboard useless since I could never touch the right spot.
Things do settle down over time, but that sluggishness still remains some of the time. What helped me the most was to enable developer options and turn on "Show Taps". That confirms a tap was registered and shows where is was, helping with feedback and making the keyboard more useful.
Charging
Charging is done with a magnetic attached cable. The box came with a small USB power brick, and the USB to round magnet charging cable. I have never used the supplied power brick, and have had no problem connecting to any USB power source. I also bought a third party USB C to magnet off Amazon, and use it the most of the time. In short the watch is not fussy about charging.
When sitting at my desk, the cable will stay in place providing there isn't too much unsupported cable length, so that is the main way I charge the watch.
Watch Display
- A monochrome digital time display, easily readable in sunlight and difficult to read in low light. Uses a lot less power than the colour display. You can run in this mode for 30 days with WearOS turned off. When WearOS is running then only Casio apps can write to this screen (other apps just have the standard time display)
- Ambient mode colour display (lowest brightness). Unreadable in direct or indirect sunlight. This is used when idle with power consumption based on how many pixels are not black.
- Colour display which uses lots of power, is readable in indirect sunlight and generally impossible to read in direct sunlight.
If you have the full colour display on and are interacting with apps, a full battery will be drained in about an hour. Consequently much use of the watch is setting the display mode you want to trade off power consumption, readability, and response time.
You can have the display activated by touch, button press, and rotating your wrist. My experience of wrist activation is that it rarely works when you want it too, and often activates when you don't. Because it activates full brightness, the battery can be very quickly drained.
Thoughts
WearOS is a lot less mature than expected. It is unclear if Google is losing interest.
Most watch faces try to be pretty and based on analog hands. It is difficult to find dense digital displays.
The Casio apps do work well. I'm glad Casio used WearOS instead of doing their own operating system with limited apps etc. However the result including their gshock style case seems pricey. A few more years of new models should improve this.
Ultimately you figure out how to get the watch to work for you, requiring more administration than a non-smartwatch. For me the benefits outweigh the hassle. I use Theater Mode from quick settings to have the time showing most of the time.