I'm thinking of buying my first AW, partly because it has cellular now and is now so much more than an iphone extension. I'm often on call for work, and I have to take my phone everywhere. I've found myself wishing I didn't have to, quite a few times. The most evident is either when I'm in the gym, or when I go for a run. No need for a belt+pouch, or an armband. Just your AW, earbuds and shoes, and you're good to go, without losing any functionality. Freedom!
Other examples are when I go out for a quick run to the grocery store. No phone means I just have to take my keys. No purse. I can totally imagine going to the beach with just my towel, a book, and the watch. Again, no phone to protect or lug around.
I remember how I wished the ipod nano had GPS, bluetooth, apps, and a means to get help in an emergency. Now it does, and they called it Watch