I attended a funeral the whole of yesterday from 8am until 9pm, and I started out with my iPhone on 62% and my Apple Watch on 100%. By the end of the day, my iPhone had 21% (used during downtime at dinner and travel - around 2-3 hours total) and my Watch was sitting at 48%, granted I was playing with it a lot.
I'm very impressed with my Watch's battery life so far, it was servicing me notifications left, right, and center from my phone and I barely ever pulled out my phone when I didn't need to as a result. It was great.
I am still to explore the possibility of giving my Watch a cellular plan but I'm still not quite versed enough to know what kind of benefits and what kind of disadvantages it might bring, as I've heard I might need to pay more to let my Watch be cellular-enabled.
Also, I find the big red dot sexy in my opinion. It screams "I have the expensive Apple Watch with cellular enabled" and I love how much of an asshole I sound for it. I also use a red watch hand and general red theme anyway so it fits nicely. A shock that it's not in a purple theme, I know.