I love reading other people's commentary. Of course, the downside is seeing opinions that differ from one's own. I had to say, this movie was pretty darned funny.
Of course, the folks who have seen the play on stage will say the movie was a poor replica; it is their duty as "insiders" to knock any reproduction of what they felt was especially theirs. The screenplay was by the same man who wrote the play, and he sculpted it very carefully. To knock the movie is to knock the playwright, which to any Durang fan is quite the slight.
As for the heavy-handed approach to Catholicism; why not? I'm sure, if Durang had suffered through a Jewish school of the same nature, we would be seeing a film and/or play based on his days with the Semite community. He just happened to be Catholic, and wrote a brilliant satire of what he knew.
And of course, there is the erratic pacing of the film. Odd sequences, strange juxtapositions, etc. It is all very confusing at times, but it all serves a purpose. If one has dealt with Durang before, one knows that his delivery is always quite odd, and always biting. The performance by Keaton actually emphasized the strange nature of his writing, and while it might not have been as stellar as some stage performances, it deffinetely served its purpose.
Basically, it is an odd film. The words of Christopher Durang presented by quite the cast of actors, coupled with a pretty decent director, brought a brilliant play to (recorded) life. I can assure you that any misscomfort you feel was fully intentional. It takes you on a rollercoaster from hillarity to shock to horror, all the time driving home a very blatant message.
And by the way, non-Catholics get the jokes, too.