No Perspective: Everything in the image will be in focus. There will not be any depth in the image and it will appear to be flat.
1 Point Perspective: With only one viewpoint, it draws all the attention and focus to the point where the lines converge (viewpoint).
2 Points Perspective: It also attention and focus to the viewpoints. The addition of another plane adds more depth to the image than a 1 point perspective.
3 Points Perspective: Usually emphasizes on the scale of the subject and imposes its personality on the viewer. Again the addition of another plane adds more depth to the image than a 1 or 2 point perspective.
More than 3 point perspectives: As the number of viewpoints increase, the depth of the image also increases. However, it becomes more difficult to focus at a certain point in the image with multiple viewpoints. With no focus points, the viewer becomes disorientated and confused.