No it isn't.
It can always be better, but it is more than serviceable as it is right now, and isn't a real issue.
Unless you are too lazy to plug in more thing every night.
I personally don't like the Apple watch approach to this category at all. Even if I was going to use an Apple device again.
Tiny little app buttons on the face and tiny little individual apps. And nightly charging.
Battery was the reason I went for a Note 5 to replace my Nexus 5 (I also dabbled with the 6plus and a month with a Nexus 6). I actually had the iPhone 6+ for a couple of weeks, my wife got me one. Because I saw her run on battery almost 2 days (at least, to like 5pm on day 2). My Nexus 4/5/6 could barely make it to 7pm on the first day.
Also, some of us aren't sleeping a solid hunk at night when we should. I'm on a late afternoon shift right now (and was doing nightshift over the summer). Sometimes I was napping for a couple of hours in a random place and didn't have my charger handy.
Pebble has the right approach to me - it's first a watch, with some notifications. My Pebble Time Round is just like my Note 5 - good for almost 2 days. Good for those days that I forget to charge. I don't need a week, but being able to miss a day is important, or to juice up substantially in 15 min while I'm making coffee in the morning or whatever.
I also liked the lack of touchscreen. I accidentally hit my Android Wear watch all of the time.
Unfortunately a real replacement for Pebble folks is hard. There's plenty of fitness trackers and full blown touchscreen, power hungry smartwatches, but a lot less in the watch with notifications category.
