Went to the 7:00 IMAX at the aquarium (#14 for me), there were probably about 300 people there. And there were at least a hundred people lined up when I left, for the 9:30 Sunday night show.
They seemed to have some sort of problem with the projector at the start of the movie - About five minutes after the movie was supposed to start, they made an announcement saying "We're going to be starting the movie in five minutes, thank you for your patience." About fifteen minutes later, they made another announcement, "We'll be starting the movie in just a moment, thank you for your patience, and this movie is well worth the wait."
And even though the movie's been open two months now, at least two people gasped audibly when Spock Prime appeared. And the movie got a round of applause at the end.