I think this is a very nice portraiture of your father. Only change I'd make is to crop out the lady? in the background left. Should be enough room not to lose the length of the walking cane here.
Decent portrait. A few things. Go back and do it at magic hour to get rid of some of the harsh highlights and squinting. Try for a shirt that doesn't compete with his face. A solid color if possible. Crop the person out of the background. Darken the bottom slightly a bit and the left edge quite a lot but blend it. You create the depth by the highlight behind him and the fence vanishing point. The problem is we should be looking at his face but are led off by his shirt and the lightness on the left side of the picture. Try to get the element so we are drawn to his face a bit more. A good start.