My favorite features are being able to control music and podcasts from it. I can be handsfree with my airpods and don't need my phone around for it. I also like receiving instant notifications of texts, calls, our motion sensor cameras on our house, etc. without having to keep my phone nearby or dig it out of my purse every time. Also nice for when I'm in meetings at work.
I will caution though about the hard fall detection feature on it. I got my father an Apple Watch for Christmas. He was out to dinner last week and accidentally hit his watch on the table while raising his arm up, and it set off the hard fall detection. He didn't realize that at the time, so when he didn't respond to it, emergency services were called and the emergency contacts designated on his iPhone were notified. I'm one of the emergency contacts and received the notice immediately on my Apple Watch, so I of course called right away to make sure he was ok. When he was, I knew it was an accident so he called the emergency services back, but it was too late - the fire truck and ambulance were already pulling up in front of the restaurant! Needless to say, we turned this feature off. Its a great feature in theory, but neither of us trust him to respond to the detection right away if something like that should happen again.