watchOS 2 has made my Apple Watch have even better battery life than before. It has now around 50% battery power left after using it for 12 hours. Incredible, and trust me, I use it a lot.
Personally I sleep with my watch on, so I charge my watch when taking a shower and brush my teeth before I go to bed every night. But with such a great battery life as it has now, I can probably have it for a complete day (24 hours) before I need to recharge it.
watchOS 2 also made it a lot faster, the apps opens faster and feels more smooth now. Especially the native apps. And it's really great to have all the third-party complications that you can choose to add to the watch faces now. And also the glances starts faster now. Probably because of the new native apps.
watchOS 2 simply makes the Apple Watch feel more like a real iOS device. It makes it even more useful than before.
I can highly recommend everyone to update their Apple Watches. It makes a huge difference.