I lived in Istiklal for five years. Taking long walks already has so much meaning to anyone, but, in Istiklal, with its diversity, complexity, and its crowd, just walking is a more special and enjoyable experience.
In Montreal there are many special, "walkable" streets but I believe that St Catherine is just as diverse, crowded, and unique as my street back home.
Walking completes the city in your mind. When you raise your head a little bit more, you take in the Art Deco architecture of a depanneur, or you discover a quint cafe, or you learn from some classy Montrealers the best place to have a midnight snack and the more you interact with the city landscape, the more it belongs to you.
As it gets a little colder, it is worthwhile to mention something called the “St Catherine effect” which is the phenomena that it is less windy and warmer than most of the other streets, just saying.