Ventajas
I was a teaching assistant for the physics department as a grad student, so I was very happy that for 20 hours of work a week I had tuition paid for and a livable stipend. The students were generally decent, if not always interested, and my supervising professor was excellent. I heard from co-workers that this was not the case with all of the professors you could possibly teach for though. As I think is typical of teaching, a lot of the time I felt as though my efforts were not appreciated by my students, but I realize that does not have to do with Rutgers as a school or employer. We also had fairly useful new teaching assistants training sessions throughout the semester to give us a crash course in teaching methods and how to deal with classroom management.
Desventajas
Some professors (though not mine) give very little guidance as to how they expect you to teach the class, students do not always want to be there (which means you often feel a though your teaching is doing no good), and the grading is always a chore.