New in iOS 9, out later today, is a Batteries widget, which lets you see the charge levels of your iPhone and Apple Watch. Some people may find this useful, but I wonder if it’s really much of a time saver. To see how much charge is left on my Apple Watch, I just glance at it; I have a watch face where the battery complication is visible. And for my phone, it’s the same thing; as you can see in this screenshot, it shows at the top of the window.
But, if you don’t display the battery percentage on your iPhone (Settings > Battery), and want to see something more precise than the little battery graphic, you may find this useful. Same thing with the Apple Watch; if you don’t want to show the charge level on the watch face, then you may want to check your charge level in this way.
Too bad this doesn’t also display the charge on my MacBook…
Update: I realized, when walking today, that this widget shows the charge levels of all connected Bluetooth Devices. I only had my Apple Watch connected to my watch the other day, but, today, I noticed the charge level of my Bluetooth headphones. That’s actually a very good thing, because there’s no way to see the accurate level of these headphones’ battery.