I haven't yet had an Apple Watch report from any of my patients, but I wished quite a few had an Apple Watch. I've had quite a few reports from patients about racing heart, and in many cases the in-office ECG captures a snapshot in time when they invariably are not having those symptoms. That necessitates ordering a longer-term heart monitor for them, which is unpleasant for them and in many cases also doesn't show anything. I don't honestly know that readings from an Apple Watch would change the way I manage things if it didn't show anything, but if it did capture unusual signals then I could imagine some instances where it might.
The main criticism of the Apple Watch when it first came out with the atrial fibrillation detection feature was the fear that it was going to have a lot of false positives, and that the medical system would suddenly receive a lot more requests for testing needlessly. I haven't seen any data on that, but I also haven't heard any complaints. Personally, I'd be worried that the Apple Watch may provide a false sense of security for some people, but I also haven't heard any stories of people not seeking medical care just because the Watch didn't report anything.
Of note, I also appreciate Apple's fine touch with the ECG functionality. I bought a new product that was a single-lead ECG, similar to the Apple Watch but working a bit differently, and the amount of signal noise was unbelievable (and basically made it unusable for all but the most perfect scenarios). Apple must have some impressive signal-smoothing algorithm at work, as these are some of the best-looking graphs I've seen. It worries me that some of these may be missing fine signals, but the Watch was never designed to replace a standard ECG.