I see the pros and cons of working out with a partner. You have motivation to get the job done but you are also relying on someone else to push you to the limits you should be pushing forth for yourself. The dilemma I often find myself in is finding a balance between workouts with people and still having your own gym time. Everyone is different – people have different goals, different opinions, and different methods.
Eating right and following “diets” I think are easier with the buddy system – especially if you work with the person. You can motivate each other to eat properly, to put down the afternoon snacks and to overall improve the way you look and react to food. I find this the type of challenge I would be willing to partake.