Vietnam is one of those places that sorts travellers into two groups after they return. One group says it was fine, a bit chaotic, some good food. The other group is already planning to go back. The difference usually has nothing to do with the itinerary. It has to do with whether you arrived with any real curiosity about a country that has been through more in the last century than most people can hold in their heads at once.
What I find genuinely interesting about Vietnam from a travel perspective is how local the experience still is. You can eat an extraordinary bowl of pho at a plastic stool on a Hanoi lane and pay forty rupees for it. The tourism infrastructure has improved dramatically, but the daily life of the country has not been packaged away from you. It is still visible, still audible, still right there. That is rarer than people think.
One thing I always tell people: do not treat Vietnam as a north-to-south checklist. Pick two or three places and stay long enough to actually arrive somewhere. The country is long and the weather at each end is doing something different on any given month. The people who have the best time are the ones who resist the urge to cover everything and instead let one place surprise them.