Because iMovie is so fast and simple, even professionals have started to use it for quick, fast digitizing and rough editing before moving into the high-priced programs. You can use it for home movies, of course, but that's really only the beginning. I remember being incredibly upset to read in the 1980s, in a New York Times article, that regular videotape begins to deteriorate after only 10 years. All of your precious footage is doomed. There was no solution.
Digital video changes everything.
Your tapes will still begin to deteriorate after ten years, but now you won't care. But iMovie is only a very basic version of a full-blown film editing package like Apple's own Final Cut Pro. It offers no method of adjusting the volume level of an audio clip along its length. It doesn't let you separate the audio track from the video. And it offers no clip video adjustments, such as brightness or contrast.