Hmm, actually I can see that there's a purple vignette on his photos, and in some others it is there to varying extents... Still, they're good quality and it isn't uncommon that phone cameras have this haze. Famously the iPhone has it too..
Your lens was not clean. This purple vignette come from light being reflected and distorted by the oil film on the glass of the lens.
Also i assume the phone used ISO 800 what is unnecessary for this kind of scene. The camera sees the dark plastic and shadows and tries to lighten things up. Because the original is black and dark the camera has no chance other than using ISO 800. This results in low contrast, high noise and over brighten areas.
The camera of the 820 might not be the best. But you can get good results.