In the parts of Rio visited by most of the tourists, and where the upper classes live, most, if not all of the restaurants are either expensive or super expensive, and you don't always get the quality for your money, which definitely is not a good feeling.
Sawasdee is one of the places where you easily spend US$ 50 for a lunch without dessert and wine, but at least the food is fantastic. I have been there twice and both times the food and service were excellent. Which, on the other hand, doesn't justify the 15% they charge for the service, when in all other restaurants and bars it is 10%.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.