I've been to Nha Hang Viet Nam twice. The soup, 149 on the menu, a sweet and sour soup with a ton of fresh vegetables, pineapple, okra, rice and fish is straight from heaven. The two noodle dishes-- the large noodles-- with veggies-- were delicious.
The staff is attentive, helpful and very friendly.
The ambience is not upscale, but neither are the prices. I don't  think you'll find better Vietnamese fare at any price.