One of the larger public libraries in the GTA located on the subway line. If you need to buy anything, it's in close vicinity. Plenty of foodie places to go grab a snack or meal in between study breaks.
Great selection of books and reference materials though I tend to chill in the magazine area most often...
I find it gets quite crowded during the week when the students are in school, but barren otherwise when they're not trying to cram for their term tests or exams.