We have been to Thai Rak Thai twice now and both times we enjoyed our food but we have also visited the newer Thai Thai a few blocks away and found the food a little better there. We sampled the same dishes at both places to compare. Overall, the quality of the meat ingredients was higher at Thai Thai and even some of the spices seemed more flavorful at the other restaurant. Our chicken wasn't super tender at Thai Rak in our dishes or soup.
In the end, I would rate the food as pretty good. But I would also say Thai Thai's food was a step up. It's kind of a wash considering Thai Thai has higher prices though.
A bigger factor for us, though, was the rude service we got on our second visit. The waitress seemed completely uninterested in answering our questions or being helpful. She had a downright poor attitude. We didn't like the service at all. I know not all of the servers there have a bad attitude, but she really spoiled our experience.