It is hard to define 'good design' because there is no right or wrong answer. It is all an opinion in the eye of the beholder. To me, good design can be a number of things. When I think of what makes a good design I think of simplicity; but not just simplicity on its own. Simplicity needs to go hand in hand with elegance. To me, simple elegance is good design. Another idea of good design to me is when people design for the future. When someone creates a design so ahead of its time that it doesn't go obsolete quickly; that to me makes good design.