Greg is largely correct that graphite will out perform bamboo as a material. I have however cast some current graphite rods made by reputable manufacturers that make bamboo feel like a revolutionary material.
The biggest case for bamboo is about the experience and the situation. A good bamboo rod has a soul that most graphite rods lack. They are a pleasure to use on small streams casting small CDC dries at rising trout. I have also used them to throw double nymph/wet rigs and they are more than adequate. I don't suggest using one to try and subdue a large tarpon in windy conditions.
In some situations there is just no more enjoyable rod to use than a finely crafted bamboo rod. That is the great thing about the industry today, as consumers we have a wide variety of choices in gear, whether we want the fastest graphite rods, a slower fiberglass stick or a high dollar bamboo, the choices are almost endless and appeal to everyone's tastes.