Outside the forum?
I don't think so as the service is hardly visible on the top search results of different search engines if someone is looking for image hosting sites unless if the person types up the full name of the search in the search space.
Also, there are very few forums that are fashioned like bitcointalk when it comes to posting images so this would make me think the Bitcointalk and altcointalk members are mainly the only peoples frequently using the service
Yeah, that's pretty much what I meant - btctalk forum members would use it in other places (and maybe recommend it to others etc), like the altcoinstalk forum, or other, lesser-known forums that use the same or similar engines.
I know I do, and probably I'm not the only one.