I've been to Vietnam a number of times, although only twice to former Saigon. Speaking with local people has been achieved in English, but the interactions both within and outside of Vietnam have been interesting and I'd like your take on the matter.
A little history if you need a catch-up
Since April of 1975 the city has officially been Ho Chi Minh, renamed for former president of North Vietnam, Ho Chi Minh, who played a huge role in the conflict and reunification. He was prime minister and then president throughout most of the Vietnam War, right up to 1969.
Is it Ho Chi Minh or Saigon? Is the sun rising or setting? What's going on in Vietnam!
However, despite the celebration, many people both within and outside of Vietnam still refer to the city as Saigon. My personal experience is that the older population stick to Saigon and I can't help but wonder if the younger population only used Saigon when speaking to me in English;
Despite nearly 45 years of official history, I don't often encounter people outside of Vietnam who call the city by its proper name, Ho Chi Minh.