I know you are going to say "Oh no a story about hamburger!" Well just take a listen. I have always been a big hamburger eater. Long before Burger King or McDonald's I loved hamburgers. However it was not until I bit into my first Natural Grass Fed Beef Burger that I truly tasted what a hamburger was.
A lot of it has to do with the parts of the cattle that are used for hamburger at the meat processors, but the flavor comes right from the raising of the cattle in a natural, healthy manner. This is true even with grain fed beef. If you can grind the beef yourself it is even better, because you can use sirloin or any other cut even filet mignon (true burger supreme). Using the fatty left overs from the butchering is a modern industrial business practice that now just labels ground beef as 80% less fat, etc., this means nothing as to the quality of the ground beef. If you have a butcher at your market picks your cut of meat and asks if he or she will grind it for you. You will be surprised at the difference it makes.
The grain fed beef tends to be fatty because that is what the USDA grading system is based on (more marbled fat the higher the grading). This of course means more fat dripping off the burger when it cooks and so a reducing in size and a big messy clean up.
The big thing is that since natural grass fed meat is leaner than feedlot and industrialized beef it does not shrivel up into nothing when you cook it. It retains the shape and size you pat out when you make the burger. The juice is not water, which has been added to the ground meat to increase the weight, but the natural juices of the meat itself. A lot of people think that the water or what some times looks like blood is from the meat, but when a cow is processed the blood is drained and the water is reduced even more if the meat processor dry ages the beef. This concentrates the flavor into the meat.