Always busy, but I go there around 2 pm on Sat or Sun and it is quieter then and I don't have to wait for a seat.
The food is superb a so cheap for the quality. It is definitely authentic Thai, when my neighbour asked did I come often as it was strange to see "foreigners" in here!!!!! He was a Thai student.
The prices are great, the choices far too many, and the only down side is that to get as many people in as possible the seating is mostly backless large stool type. I like to lean back so I try to get the seating against the wall.
If you haven't been then go there. Easy to get to, being in the Capital Square centre next to the Capitol Theatre and convenient to all buses and trains.

Approximate cost: $10

Great atmosphere, friendly staff, good coffee and food, priced well and affordable. The owner, David, is very friendly and runs a clean coffee shop where you are welcomed like a friend. Only downside is that it isn't open in the evening or on Monday but I do enjoy the other 6 days very much.