Some good points were already brought up in the comments (IP5X, USB C charging), but I have the feeling that it's also just not a good fitness tracker/smartwatch. I see a single unboxing of the watch from three weeks ago on Youtube and zero reviews on YT or websites. Just posts based on their PR release that it's available now. (Though some clearly already shipped.) Thus, it's unfortunately very likely that the produ…
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.