The basic plot of "Congratulations, It's a Boy!" - a man finding out he has a grown-up son - wasn't new even back in 1971 when this movie was made. Still, the movie overall manages to be a competent telling of this old story. The movie has some big faults - Bill Bixby's character finds out he has a son in the first five minutes of the movie, so we don't really get to see how this changes his character. Also, there is less interaction shown between Bixby's and Darrell Larson's than you might think. On the other hand, their few scenes do have some genuine dramatic weight to them, and are surprisingly effective at times. Also, the movie isn't totally serious - there is some comic relief, and this comedy is genuinely funny at times. In the end, the movie is an okay way to pass 73 minutes of your time.