I paid full price some time ago for my Nexus 5.
I am happy with it; well worth the price. Its panorama is not as good as the native app (Google Camera), and it doesn't have photosphere, but other than that it's my camera app of choice.
You have to fiddle with the settings in order to find the best combination for your camera, so it takes a while to set up after you install it.
The DRO setting (in the Single Shot mode) is ironically often better than HDR, depending on the lighting, which is good news as DRO is faster.
If you don't already have it, get it. At that price, it's virtually free.