Advantages and Deficiencies of Gourand Shading

Advantages of Gourand Shading: this eliminates the intensity discontinuities related with the constant shading model.

Deficiencies: Linear intensity interpolation can reason of bright and dark streaks termed as Mach bands to show on the surface, these mach bands can be eliminated through using Phong shading or through dividing the surface in larger number of polygon faces.

Note:  In  Gourand  Shading  due to  consideration  of  average  normal,  the intensity is standardized across the edge between two vertices.