Fall detection seemed like an awesome feature until it false positived a ton. I eventually disabled it on my Series 5. Clap your hands? you fell. Use a hammer? yup. fell. Swat an insect with your hand? again, you must've fallen.
I hoped constantly telling it 'I did not fall' or 'I'm ok' before it inevitably tries to dial 911 via your phone would 'train it' but nope. It had to be turned off.
Ironically, the one time I did come crashing down after slipping on ice and caught myself with my left hand, yes, the one actually wearing the watch, it never triggered. I was ok, of course, but after that, I felt it wasn't effective when needed, and too often triggered for no reason.
Forget the ECG feature if you're the type who has an odd resting heart rate which is quite high, such as myself. Doctors tell me it's normal for me, but my resting rate is usually in the 90s. That tends to kill ECG because anything above 80 is considered 'inconclusive'. Also, if you don't fit the demographic of atrial fibrillation, it's useless, as that's really all it looks for. Even though the Series 3 lacked ECG, it could still detect Afib, so paying more for a broken feature for some people that looks for the same thing (but with pretty graphics) isn't worth the effort.
The Apple Watch is excellent otherwise. It lacks ability to really get third party faces, and most haven't been updated since the first Series 0 came out, so the selection can be limited. But it seems indestructable. I've abused my 5 (at work) and it shows no obvious signs of damage, unlike multiple Galaxy Watches. The 'radio' app has no equal on other watch brands, including Samsung. Only the Apple watch has that app, which beats Spotify and has offline playlists. If you're into 70s through 90s music, there's a playlist for you and with AirPods, it's quite nice during exercise. Apple Pay is faster than Samsung Pay (less steps). Notifications are quite customizable.
Just turn off the move goal at the end of the week challenge. I couldn't imagine what effect it would have on a 70 year-old, but I swear it's algorithm was trying to kill me. I'm a tiny guy weighing around 150 lb, and thin frame, and all I wanted to do was maintain my current weight. But it kept adding new move goals that were totally unrealistic for myself. It wanted me to do like 30,000 after a few weeks. That would have given me a heart attack. It's hard enough managing 8,000. That is at least 2.45 miles for me. I can't imagine beating 30,000. I think you can turn if off but I was unsuccessful (another in the list of Series 5 bugs for me). I just turned on DND all the time.