There are only about 400 units in existence, and they just started shipping June 30:

https://www.kickstarter.com/projects/unawatch/meet-una-the-m...

so it's been out for less than a month. That's why you've seen zero reviews on websites, it's an indie Kickstarter. They don't have the marketing budget of a big wearables brand.

It has a GPS, IMU, and heart rate sensor: That's enough, obviously, to track activities, workouts, and health which their competitors do with the exact same set of sensors. It remains to be seen how accurate those are, or how well the manufacturer and community can develop useful algorithms to turn raw sensor data into activity logs and actionable health insights, but step 1 is to release an MVP to get people wearing the watch and logging data, and step 2 is to use the data to improve the algorithms.