So here's the scoop about USP.
Academic quality is pretty good (at least so far from what I've seen). I don't know if it still has the reputation it once had, but job providers in the area still do know the name. Profs are usually available for office hours, and will help you if you ask them. It is not as hard as most people make it seem, and most people spend too much time studying.
Which brings me to social life. Probably the best option for you if you want a social life is to go Greek. Otherwise, there is not much to do. On the weekends, everyone is either studying or at home. The university tries to provide activities, but no one goes. There is always the city to go out to, if you find someone who is not studying to go with.
Other things: very nice gym. Overpriced meal plan that does not provide food of the quality it claims to provide. Last year the dean of students tried to quash frat parties with her iron fist (but she's gone now, we'll see what happens this year).