One of their key selling points to me over Fitbit is that they support HealthKit on iOS.
However, there was a critical bug that prevented the HK integration from working properly.
As someone who knows HealthKit pretty well, I went in circles for weeks trying to get them to fix it - every response would reset the thread back to the agent walking me through basic steps, no hint of reading the ticket history.
Super frustrating, so I just stopped using it at that point.