I downloaded ClassPass after meeting someone who told me about it. I recently moved to a new city, so it's cool to see what everything that is out there that I haven't found through my own research.
Seems like certain businesses don't offer the same classes via the app regularly. The person who told me about CP, I met her at a tumbling class, and she told me she found that class on the app. Ever since I downloaded it, I never saw it on there.
Seems like it's good if you're shopping around for finding places/activities you like, but once you find a place you want to go to regularly, you're better off buying a membership through the actual business. I imagine they don't get a big cut from CP, so that's why some businesses don't regularly offer classes on that platform.