Line up seemed long but it actually moved quickly. They don't take day of reservations but if you call in advance, they will accommodate.
Staff were friendly and the ambience was energetic. The food came really quickly and were all really yummy. The only downfall of the night was that they misplaced our order of chicken skewer which and the order of spring rolls weren't crispy.
Overall, I would recommend PAI as it is one of the better Thai restaurants in Toronto in my opinion.