If I am in a crowded theater, I expect some noticeable audience reactions--laughs, gasps, scattered applause, etc. I find it enhances the movie-going experience. If I want silence, I will wait for the dvd and watch it at home. Some of the best movie going experiences I have had have been because of other audience members. I will always remember watching Halloween H20 in the theatre and a woman yelling
Or seeing Eyes Wide Shut with the two black women sitting behind me giving their own commentary. There is a fine line between being obnoxious and being funny, and I can see where it differs from person to person. For me, that is what makes it worthwhile to go out the theater, pay for a ticket and pay for overpriced popcorn and a drink. I do draw the line at clapping at the end of the movie though. That is completely unnecessary unless you are at the premier where the actors, directors, writers, etc can appreciate it.