Whatever tension the movie has built up is completely lost.
Any emotional investment the viewer has made has all gone.
What may have been a great movie is ruined.
The director, producers, cast etc have spent a great deal of time and effort to put this thing together only for commercial and news breaks to spoil it all.
If it's the first time you've seen a great movie then your left feeling it was simply mediocre. And it's too late, you'll never see it for the first time again.
That's why movie pirates annoy me, they see a rubbish copy of a movie and then think they're qualified to judge it's quality.