I guess it is always a warning sign if you go into a restaurant at 7:30pm and you are the only customers. The setting was both good and bad -- overlooking the hotel pool, which was nice, but perhaps someone might have turned some lights on as it was tricky even to see the menu by starlight. The wooden seats could also use cushions.
Having ordered 2-3 course at other Vietnamese restaurants only to have all the food arrive at once or out of order, we thought we had now sussed out how to do things, so we ordered soup and drinks only. When that eventually arrived half an hour later, we duly ordered appetizers, The soup was moderate at best. Continuing the plan, when the appetizers arrived we then tried to order main courses only to be told that the kitchen was closed now as the chef had gone home. Really hopeless!
So, be warned when going into an empty restaurant that there is probably a reason it's empty. I'd also highly recommend that you become one of this restaurants many potential customers who have chosen to eat elsewhere.