The US trailer gives some context for audiences who might not be as familiar with the whole Chunyun phemomenon:
And this seven minute clip gives a sense of the family conflict director Lixin Fan was able to capture in the film:
If you get a chance, I'd definitely recommend seeing it. http://www.zeitgeistfilms.com/playdates_new.php?directoryname=lasttrainhome has a list of dates.
In Boston, it's currently showing at the Coolidge Corner in Brookline, the Kendall in Cambridge, and the West Newton Cinema. In New York, it's now at the IFC Center. In San Francisco, it's at the Shattuck in Berkeley, the Lumiere and the Four Star in SF, and Camera 3 in San Jose. It's also playing in Hartford and many other cities around the country. But check the above URL for more detailed info.