This is pretty much the definitive camera app to have on any Android right now, period. Takes brilliant pictures, is wildly customizable, and all for the price of 0.
One gripe with it, could you perhaps make it prettier? In a world with Material Design, this app sticks out like a sore thumb. Together with making it better looking, I feel it needs to be more intuitive. The controls - while there - take a while to find, and require more than one tap to reach. Perhaps you can try emulate a "real" camera? For example, Manual Camera has the best-working dial I have seen yet, and it make it an absolute pleasure to use. The exposure slider in Open Camera, in comparison, is laughably bad. The same thing for locking exposure - the camera app on the iPhone does it best, I think: hold to lock exposure and focus. Not to mention swiping up/down to adjust exposure. Also, a button of the most common features would be welcome, such as a button for HDR.
I have also noticed a couple bugs: taking pictures on burst mode makes my phone crap itself. It takes the burst shots, granted, but they're all blurry because my phone froze while taking them. Speaking of burst mode, iOS does that well, too - hold shutter to take burst pictures. Another bug I've noticed: digital image stabilization does the opposite of what it's supposed to. For the record, I've got a OnePlus One, running CM13, if that helps.
Apart from those minor nibbles, this is a fantastic app. 4*.