It’s a very promising algorithm，beacause it generate approximate results very quickly, however there’s some issue with its convergence speed.As far as i know, the photons should not be visible to camera unless it’s caustics.Through a process of ray tracing which is called “final gathering”, the noise of photons could be greatly reduced. This method were adopted in mentalray(which is dead now).
As we can see the noise near the camera is generated by photons, while the fireflies near the lights come from ray tracing. Combining two methods giving a renderer stronger applicability and generality.
Here’s another picture rendered with blender cycles which shows its weakness.
I encourage you guys keep on developing .Overall you did great jobs ! Since cycles mainly focus on flexibility, its lack in speed makes it not suitable for complex scene . Thanks for your selfless efforts!