Hi I have been to Vietnam twice and had enjoyable time on both occasions. As Nicola said the people are very friendly and eager to improve thier English. When talking to you they can ask some "personal" questions, such as "are you married, do you have children", all you have to do is answer them honestly. I was once asked "do you have a husband", I said No, I wish I had, and the young lady who asked this question and I both laughed. The children are very polite, and sometimes ask do you have a pencil, pen or writing book, they are not begging but is only because it is expensive to go school there, and parents often sent one child to school in the morning and the other in the afternoon. On trip to Vietnam I visited a nursery school and it was obvious supplies were in short supply, so th group did a "wip round" and when we gave the money her face lit up with gratitude. I would say if you are thinking of going to Vietman - go for it - you will have an enjoyable time.
Lesley