I own and wear a smart watch, it's
Moto 360 by Motorola.
I'm really liking it so far. First of all, it looks like a proper watch I'd like to wear on my wrist. On the smart part, I get all the notifications from phone on my wrist, so I don't need to pull my phone out all the time. Very convenient after I got used to it. I can just glance at my wrist and decide if it's important. Also, I can dismiss notifications on my wrist and they go away on the phone too.
I've started using voice search a lot after getting the watch. I use it for quick searches (fact finding etc), text/whatsapp quick replies, setting reminders, alarms, taking notes etc. It also tracks my steps and heart rate throughout the day.
Now coming to Apple watch, I don't like what they've done with user interface on the watch. I don't want to fiddle around with it a lot. The app launcher UI seems unnecessary to me on the watch. Plus complex interactions like the digital crown and dedicated button for iMessage seems overdone. Looks like Google and Apple went completely far away from their usual approach. Google's Android Wear interface is very simple, whereas Apple Watch UI seems very complex.