I recall being told once that it is very common to see Vietnamese with baguettes as (the person said) that the French did leave an imprint on them). I know that colonies often adopted aspects of their colonial powers but how did French culture impact on Vietnam? Is there a noticeable impact or did they reject it?
On the whole the influence is quite small compared to China's. There are plenty of French-style buildings in Hanoi and Saigon to remind people of that era. The tallest building in Vietnam up until 2 decades or so ago was actually a French-built cathedral.
There exist dozens of borrowed words such as [(ét-)xăng] essence "fuel, petrol, gasoline", (xà-phòng/xà-bông) savon "shampoo, soap" and (cà-phê) café "coffee". Again this is nothing compared to even English but most notably Chinese (50-60% of all Vietnamese words are Sino-Vietnamese in nature).
Vietnamese cuisine also benefited from the introduction of the baguette which was altered to become the famous Vietnamese bánh mì of today. Various other dishes like Phở are said to have been influenced by the French (pot-au-feu in this case). The writing system of today was consolidated into usage thanks in part to the French but it was already being used prior to their arrival.
On the whole there are some reminders of the French in the form of architecture, vocabulary and gastronomy. Not much else I'm afraid.