Japan currently has the highest life expectancy in the world. Some credit this to their diet of low fat and a excessive amount of green tea intake (~6-10 cups a day).
I drink about 2-3 cups a day and am able to maintain nearly the same weight I had coming out of army basic training without nearly the workload.
Even if you disregard the potential weight loss benefits, it is a fact that green tea has antioxidants that may help prevent cancer. Also, its better than soda.