I've had my Apple Watch for a few weeks now, and...I love it. I was lukewarm, but now it's reached the status of my wrist feeling lacking without it, while ironically it's very comfortable to wear so I'm not necessarily aware of it unless it isn't there.
I even warmed up to the strap. I don't know whether the heat of my arm has loosened it up or I've just gotten used to it, but it is now very flexible and comfortable. I canceled my Milanese loop order because I'm just fine now with my Smurf-blue strap.
I've changed a few things in my daily life processes to work with the Watch, since it's here to stay. Scheduling has been an issue for me. I like paper planners (I have a whole board for them on Pinterest). My brain apparently needs the visual layout, and no matter how easy iPhone calendar apps make it to enter appointments, I manage to jack it up. Much easier to just flip to a page and jot it down without messing with tiny buttons, wheels, or keyboards.
When I got my watch I switched to electronic calendars because that's the slick, hip, and cool thing to do. It IS nice to have your next event right there on the watch face. Still, I was late to stuff or went on the wrong days and decided I might as well integrate a good old fashioned planner back into my life (I found a great deal on a purple Malden Filofax on eBay...coincidence?).
There are things I do prefer my phone or watch over paper for. I like reminders, and I use Siri constantly. I also keep my grocery list in Reminders because it's so easy to say, "Hey Siri, add bananas to my grocery list." And with the fab Reminders Nano app, I can pull that stuff up via a glance on the Watch, which may make me look stupid in the store but is much handier than balancing an iPhone 6 Plus along with OJ and eggs.
I've adapted my iPhone calendar usage for the watch. I use the Modular face, which dedicates a good third of the screen to the next calendar event. I don't need that because I've got my actual schedule in my planner, so I coopt the space to write reminders to myself; however long I time the "event" for is how long the reminder will be on my wrist every single time I look at my watch. I can fit an entire short-run grocery list into a calendar event in this way so I don't even have to push buttons in the store. The effect is much like walking around with a Post-It note on my arm. I love this hack so much. There's usually at least ONE thing a day that I ABSOLUTELY CAN'T FORGET but am likely to forget if I have to pull up a list to look at it.
And of course, the watch can't be beat for location reminders. I went to the trouble of entering the address for the local gas station into my contacts so the watch will remind me to stop for gas when I drive by. It's the little things in life.
Finally, I'll chime in with most other commenters who note time saved messing with my phone. I have fine-tuned my watch notifications, finally, to the Goldilocks level (not too few, not too many: just right). Typically now when I pull out my phone it's to do something specific, as opposed to previously when I just checked it all the time to see if I had missed something important. And then, while I was there, checked Twitter and Tumblr and...
Anyway. My little calendar hack isn't really brainiac stuff, but I'm finding it danged handy, so let me know if you try and like it!