The hardware seems nice, but to me it is a huge red flag that (1) the communication between the sensor and the phone is encrypted, so that no third-party app can ever be developed, and (2) it seems that your health data is uploaded to the "cloud" without any opt-out or possibility for local operation.
This looks like it' using the method that was mentioned in the article too, it needs regular calibration with a cuff (which they include with the product).