Even just a few days with them can do much to heal the loneliness and longing for home that these people feel. Furthermore, the families will miss their children and would be most pleased to see them again. Catching up on lost time and reconnecting with friends and family at home will be an invaluable experience. However, the most obvious disadvantage is cost. Flights, especially flights during the holiday season, are notoriously expensive. A single round-trip ticket can wipe out money earned over a whole semester working part-time jobs.
Then there is the matter of presents, even just minor trinkets, for the relatives back home. All told a foreign student, and his family, may have to spend hundreds, or even thousands of dollars to see their child for Christmas. Related to the first disadvantage is the separation from friends in University. After all, they are not going to follow the student back home and will be missed. Another advantage is the relaxed, familiar home environment that a foreign student will return to.
In the land of his birth a student will be more relaxed and better rested for his up coming return to the mundane world of university. However, this also means that he will not have access to the school library and other resources of the university. Then again, the internet will help bridge that gap. Finally, with so many relatives and friends to catch up with the foreign student may not be to find time to study at all. When he returns he may find himself completely unprepared to face his professors.