Theres no doubt that Cortex Camera takes clearer photos with less noise in low light than any other camera app I have used (ProCamera 8 - my previous go to for night shots, ProCam 2, & Slow Shutter!).
However, it should be mentioned that sometimes photos have unwanted results such as blurred areas or jagged lines caused by not using a tripod or a moving subject.
It would be nice if there was more features such as separate focus/exposure controls, and manual controls that were introduced in iOS 8. The UI could also use a change. It feels very basic and cheap. It doesnt look as nice as other apps.
Overall, its a great concept and it does create good quality photos in some situations. I wouldnt say its worth the $2.99 price tag. I think $0.99 or $1.99 would be a better price.