I don't do a lot of file conversion and I only use their free level of service. But every once in a while they come in really, really handy. Their site just works, no waiting or anything. The description of five stars here is "You love it so much you want to tell the entire world!" And in this case for me it's no exaggeration, because the world is a more convenient place because Zamzar is in it.
Thanks so much for the great review, Steve! We're so glad our site helps you out!