You will always find people who have had success in a particular way of dating because there is such a vast number of variables at play. Long distance relationships for the most part give people a false hope or a lack of control in the outcome, and in my opinion kills your self-esteem.
When I think back to a girl I was dating during my time at university in Port Elizabeth, I recall how the tension escalated when I moved to Johannesburg. A year later she moved to Stellenbosch to pursue an Honours degree in Chemistry. I would never again get involved in a long distance because it was doomed from the beginning. The signs were there but I chose to ignore them.
Some fascinating research from the Journal of Family Relations is that couples who marry from a long-term relationship may still be in the idealized state. This impairs their ability to be realistic in their evaluation of the other. Your biggest challenge today is not even that the person you are dating is another city. Imagine where they are in their minds when they are chatting away on Facebook or MXit?