Been going a couple of times there and happy to give Pai a good review.
First of; make sure to reserve or arrive early; the place gets packed pretty quick.
The food is always delicious. My favorite dishes are the Khao Soi, the spring rolls ans skewers. The dishes usually come quite fast and well made.
The staff are very friendly, polite and they know their menu well. They always take the time to present the dishes when they deliver them to you.
They have a section where you sit on cushions, it brings a nice experience.
The prices are really competitive for downtown core.