I've had my Moto 360 connected to my Nexus 5 for about a week now and the battery life of the watch has been great. Battery life is all relative of course, because everybody's usage patterns are different.
I pick the watch off the charger around 7AM and put it back on around 10PM and it usually has about 30-40% left on it when I'm done.
Google handles both my work and personal email accounts, so that's nice. I only have notifications for my priority inboxes though, because I didn't need the constant vibrations for marketing email.
Using the watch instead of my phone has helped my Nexus 5 battery as well as I don't light the screen up nearly as often to check notifications.