From my personal experience and that of my friends with vietnamese spouse, the main complain they have is having to feed their in-laws. Although not all vietnamese in-laws are the same, but the majority are very much in need of money. Having their daughter married to a foreigner, they feel that they have solved their financial problems from then onwards. They will stop working, i mean not just the parents, but other siblings staying with the parents. They will expect the daughter to remit a few hundred USD a month to `help' them. From time to time, they will have extra demands like wanting to buy a `motorbike' or even grandma needs to see doctor.
The educated and non-educated in vietnam see a lot of difference. The educated are more understanding and often stay in the city while the non-educated are directly opposite. But like what were discussed before, they are more ways than one to minimise such extra burden.