This place is truly a gem, and probably the best old-school hardware store in Toronto, certainly within the urban core. It's been there for nearly a century, and they have almost anything an average person could need.
Moreover, the staff is helpful and very knowledgable. They can talk to you about how to approach a project, suggest various solutions, and tell you about all their products. It's a place you don't need to feel embarrassed if you don't know the right technical language, and almost anything can be pulled from one of the many nooks and shelves around the store.
Places like this are a dying breed, and I treasure stores like this as cultural institutions and repositories of disappearing knowledge. You'll never get service like this at a big box home improvement store, and you'd be hard pressed to find anything comparable at most mom-and-pop hardware stores as well.
A great place to check out, and a business worth supporting. Check out what The Star had to say in 2014:
http://www.thestar.com/news/gta/2014/09/17/after_90_years_jacobs_hardware_still_has_what_downtowners_need.html