I've been here a few times and always had the amazing Pad Thai. My friends have had other things, and none of them spectacular, but the Pad Thai was AMAZING. None of that over-ketchuped nonsense here, Queen Mother's Thai chef makes a really good Pad Thai. The sauce was really good, tamarind with a hint of peanut. Large pieces of chicken and shrimp and fried egg goodness. The Pad Thai comes in three levels of spiciness, but even the most spicy one doesn't take away from the flavour.
Another must-try is the calamari -- crispy on the outside and really tender on the inside. I've always had calamari with tzaziki, but Queen Mother serves it with sweet chili sauce, which is a really nice fusion taste.
Service is fast and friendly but could get hectic when the opera rush comes in (since the COC is just down the street).
P.S. The Pad Thai is $2 cheaper on the lunch menu, but the dinner version is almost twice as big as the lunch version. No dinner menu until 5:30PM!