There is a reason it has a very busy lunch and weekend crowd- it's a reliably good, hearty, reasonably priced restaurant with no frills and good tasting.
Cash only can be a bit inconvenient at times, but it is clearly posted when you enter so there is no surprise.
The pho is huge and the rice dishes are also good when flavoured to one's raste with the gambit of spices and sauces provided.