I've been here at least five times now. My last visit was on Tuesday afternoon. Surprisingly, there was a ton of people on a weekday. I really enjoy rock climbing.... If you're the same, then you might not enjoy The Hub as much. The Hub is known for its boulder, in particular their massive dragon sized bouldering surrounded by a large foam pit. Their rock climbing with belays and auto belays is smaller as their focus is bouldering. Overall, if you're looking for a fun sporty activity or want to practice your bouldering, the Hub is a great place located in Markham near the 404. However if you want to rock climb with a belay, then there are other options available.
Tip: weekends are pretty packed. So be prepared to take turns or watch carefully if anyone is climbing near or above you. The Gym is not included in your day pass.