If done right, it takes a good hour to drink it. It is especially nice with a good friend or two (you all have to drink out of the same straw, so it better be a good friend) I just saw some of the good stuff on an auction site for cheap which means I'll be stocked up for awhile.
It might make you @$it like a duck (although I have never had this happen) more likely, if its not prepared correctly you might have an upset stomach. It will however make you urinate quite a bit since one round of mate generally lasts through two kettles of water. It will also keep you up at night because it is more caffeinated than coffee.