Larger houses, larger gardens, fantastic views, considerably cheaper than properties closer to the station and, as fl0wer says, proximity to all the green spaces of Dulwich and Peckham. Those are all reasons that make the road sought after to some people. Rather obviously, house hunters have different priorities, so if you want a quick jaunt to the station and to be within walking distance of the bars and restaurants then Overhill Road isn't going to be of particular interest to you.