Well Grades are the first and foremost, due to the fact that, over here in GB anyway, you're paying around £3000 a year to study, plus (maybe) an additional £3000 or so to live. If you come out with nothing, even if you had fun, the money is pretty much wasted. In all fairness, the point of uni (or college) is to come out with a degree.
I would say social life is the second most important. You need to socialise. Yes, you do need to sleep...but at the same time I think I'm slowly becoming nocturnal. I still manage to get up for 9 o'clock lectures, but if I have the day off I usually sleep until about 1pm, and then do something in the evening/night. Maybe that will change when the weather gets better....