Yeah, they added 20 more cities yesterday, I believe. I think they started out with 13.
I feel like if I really talked about it, I would be giving some stuff away. The build up is what's effective, though. A lot of the film is kind of "meh," but then it reaches "holy shit!" levels, but I think that was the point. By all means see it in a theater if you have the chance, as it's completely worth it. But really, when I say it's effective, that's really what I mean. Perhaps a better wording would be "effectively scary." It definitely does what it sets out to do.