When it comes to Vietnamese food these are all I know:
1) They are healthy
2) They are soupy
3) They are usually cheap
Okay, these are not necessarily true, but for someone who is as novice to Vietnamese cuisine as yours truly, this is as good as it gets. So when I first moved into Sheung Wan and discovered that there is a Pho Tai Vietnamese Restaurant just a few steps from my gym (how apt, work your ass off and then haul it into a healthy joint), I made it into one of my frequent haunts.
Not a favorite, mind you, but a frequent one nonetheless.