Some people love it, but I have tried it and I can't stick with it. That is just me.
Others have had great success on it.
Basically, you can do the plan two ways-they have one where you do only the Medifast shakes/soups/oatmeals/etc., or a plan where you do the their plan where you have those most of the day, and are allowed one "meal" of a small amount of lean protein and greens-like a bit of grilled chicken and salad.
It all boils down to whether or not you can committ to eating nothing but the Medifast and the lean/green meal, for the course of your weight loss. I can't. I have to have real food. Others like not having to think about food. It is a personal thing.
You also have to think about a plan to keep the weight off, once you have lost it. You cannot, on any plan, go back to your original lifestyle-or the weight will come back. You have to have a plan for maintenance, when you near goal.