If you are a 3D graphics person you will most probably heard of Vray. What is Vray? It is a very good 3d rendering systems. It is used by many 3D and design professionals.
One the other hand, there are talented individual who write 3D programs for free. Yafaray is a powerful open source 3D rendering systems. Both sottware are capable of producing very nice images.
So how does Yafaray compares to Vray? To find out read: Yafaray vs Vray