Mate is great! I love the bitterness of it too.
It helps your brain think clearly, gives you an energy kick, and helps you to burn fat. It gives you energy to be alert and aware but also won't keep you up all night like caffeine. In fact, it makes you sleep more soundly.
Basically, yerba mate is prime for socializing (sharing with others), feeling better, sleeping better, losing weight, studying, and exercising. Drinking it before exercise is great because it somehow delays the burning sensation you get at the gym while lifting weights. Thus, you can lift more weights more a longer amount of time and burn more fat.