This picture dictionary is amazing. I have spoken Vietnamese every day since, well, I learned how to speak, but did not learn how to read Vietnamese as a child. This book has enabled me to see the words I already know, and I'm making great progress reading now. There are a few nuances missed by the book. For example, it does not show you which words you should use to address relatives on your father's side vs. your mother's side. Anyone who grew up in or around Vietnamese culture would know these words, indicating that the book may be targeted for Vietnamese speakers learning English.
This dictionary contains most words one would encounter in day-to-day life situations. It is excellent for those purposes. For a broader lexicon, I recommend Tuttle Compact Vietnamese Dictionary.