Fantastic! This place has every travel book you could possibly need crammed into every little nook from floor to ceiling. I've never seen a store stock so many travel books ... they must have 10 times the selection of a Chapters-Indigo.
I came after my local Chapters didn't any guidebooks covering the country I needed (Taiwan). Open Air had 4 to choose from, each the most recent edition. This is a basic operation (their inventory system consists of writing the title of a book sold on a pad of paper for re-order) but it works. I'll come here again for sure.
Just keep your eyes open for it, it's in a basement and hard to spot -- it's right on the southeast corner of Adelaide and Toronto St., down a set of stairs and behind a solid black door.