As I described, I got stacked alerts, sometimes as many as ten arriving in rapid succession with inconsistent readings (Alert: 10.5, Alert: 7.3, Alert: 12.2... etc). Sometimes the reading would actually change while I was looking at the alert. Alerts are particularly unreliable when the phone is in some sort of sleep? I'm not sure, but if the phone is inactive for a while alerts get really flakey.
Dexcom clearly knows about the problems, they continually update the app, and keep say "we're still testing it!"
I've used it on two phones, same problems.
I'm never used an app with such basic problems in its functionality. So the idea that the FDA or Apple are keeping software quality up in this space seems laughable to me.