The issue I find, which you may already know, is that the highlights on the mans face are blown (No detail to recover, see below) as the lighting on the main picture appears to be coming from slightly behind and overhead and the superimposed face, lighting is to the right and really low.
I have tried a quick edit below and looks a little better, I can try and push this a bit further tomorrow when I have more time, but hopefully in the meantime someone more experienced may help
Sorry about the delay...
1. Created new layer, on this layer sampled a skin tone (From neck area) using the eyedropper tool and, using a soft edged brush, paint roughly over the face.
2. Change new layers blend mode to 'multiply' and reduced opacity to around 60%
3. After adding layer mask, Clean up area around the sunglasses and hair.
4. Add a new Black and white adjustment layer affecting only the skin tone layer and reduced this opacity to around 20%