I mainly use it as my iPhone extension. So that I can let my iphone just sit on the charger silently when I am at home, and no need to worry about miss call etc. I keep my iphone in silent mode because I don't want it awake my baby, on the other hand, I must able to get call when I am on duty, so the Apple watch is actually a perfect tool for me. Now I can sleep with my watch, keep the phone in silent, but the alarm / phone call can still wake me up easily by the watch's vibration. And I can even confirm the caller, and choose to answer or not when I still on my bed.
Apart from that, the ability to receive real time notification during work also make my life much easier. I simply will never miss any notification. Even though I am walking in a noise environment with my phone in the bag, or talking to someone and totally distracted. The vibration on my wrist can easily catch my attention to make sure I won't miss anything.
The navigation function is good as well. I use it quite a few times. It's so simple. I can keep my iphone in my bag, don't need anything to hear the voice instruction. But just follow the vibration instruction, and then reach my destination. Again, I can do that when I am walking / talking with my friend, but no need to keep monitoring the map anymore.
Since all my family members have a Apple watch, so the force touch / imessage function of course make our communication easier.
Besides, I will occasionally use it as the baby cam. Just put the iphone at the correct place and make sure it's camera is facing the baby's bed. So now I have a baby cam (on demand) on my wrist (by using the remote camera function). Of course the screen is so small on the watch, I can't see everything clearly. However, all I need to know is the baby still on the bed but no accident (e.g. drop on the floor). So, the watch's resolution is more than enough to clarify if it's safe.