It's on the corner of Jackson and Maple in West Ann Arbor and it is some of the best Thai I've had yet. It is tucked back into a corner of the ArborLand Mall, and you'd never know it was there (look behind the bookstore).
Dishes to look for:
Talay Thai - Battered shrimp and roughy in a tamarind sauce
Guy Pad Prig Haeng - shrimp + cashews = love
Tod Mun Goong - shrimp cakes
They make a pretty decent caramel flan as well.