Tell Me About Grand Marnier, Please!?

So a friend gave me a bottle of 100mL Grand Marnier (its from France and looks pretty old) for my birthday. I've never had Grand Marnier before, so I was wondering how drunk 100mL will get me (6 feet no tolerance), what it tastes like, do I drink it by itself or mix it with something, what it mixes well with, etc. Thanks!!!