Canal Walk certainly is big. I'm sure you could comfortably spend the day exploring.
I see some reviewers complain about it having the same old retail stores. This is true, but it also had a lot of unique stores. I think the secret of Canal Walk is the fact that you can find or do most anything you need to do in one place. From restaurants, to banks, to groceries, to furniture, to clothing, to entertainment, etc, etc - it's your one stop mall.
Tip: If you plan on spending less than 90 minutes at the mall, pop into Pick n Pay, make a small purchase and they will validate your parking ticket which entitles you to a free 90 minutes parking.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.