Overall I enjoyed it. It was very funny in parts. My favorite bit was when they visited a place where Jews invent contraptions to basically try to circumvent the edict against resting on the sabbath. Really hardcore Jews won't even turn a light switch on or off on the sabbath, but this place comes up with all sorts of gadgets, such as a Shabbat-friendly phone:
Making or receiving phone calls is also a no-no on Shabbat, but technology has come to the rescue yet again. The Institute for Science and Halacha has come up with a button-free telephone. All the electrical circuits are perfectly closed, which means that in practice - the only thing stopping it from dialing all the time is an electrical disruption caused by an infra-red ray. If an emergency arises on Shabbat, you just wedge a stick into a designated hole on the telephone. A circuit is made and dialing is enabled.
Maher pointed out that what this amounts to is trying to trick god, and isn't that more than a little silly?
Mostly Maher chose this kind of low-hanging fruit. He interviews truckers, an amusement-park Jesus, and a guy who claims to be the second coming of Christ. On the one hand, you could say that he's just picking on the wackos, but he does interact with a fair number of "normal folks" who make up the rank and file of believers. I don't think the movie would have been quite as funny if Maher had stuck to interviewing university theologians, and Maher probably didn't think so, either. If you want a more serious version of Maher's approach, there's always Richard Dawkins' Root of All Evil, a documentary he put together for the BBC.
Religulous was bookended by some very serious editorializing by Maher about the deadly mix of religion and modern weaponry (a point Sam Harris makes in The End of Faith), but it felt like a jarring mismatch in tone from the light-hearted stuff that had just come before. Maybe if he'd mixed it in throughout, it would have been more effective.
Anyway, I doubt that the film would have much appeal to moderately religious people, though I don't know. Maher's basic tone is, "Come on, people, look how silly this shit is!" which I don't think will resonate very well with people leaning one way or the other, and I doubt they'd go to see this film anyway.
Still, it was very funny in parts, and I would like to see feedback from a group of people across the religious spectrum, rather than just other atheists and movie reviewers.