Been going to Vietnam every year for 15 years. Last time was with a 90 day tourist visa
this past November. I always enjoy my time there-people, food, great scenery.
That said, I'm always glad to leave after 3 weeks. (90 day visa wasn't necessary). Coming back to Thailand after Vietnam is like coming back to the States.
Its just got better infrastructure and more food choices. Health care is way better, too.
Maybe in a few more years, it will catch up to Thailand but that comes with a pricetag.
The rustic charm of the old Vietnam is slowly fading unless you get out of the cities.