The Bottom Line
I have been using Movie Maker 2 for nearly two years. It's a solid tool that delivers for an amateur audience. (This is the same audience using iMovie.) While I like the iMovie/iLife integration, I really don't like the fact that Apple has not branched out to the PC world. Of course, that would be counter-culture, but I have to say it.
While having a product that works is good, what makes a product great is easy access to training tools. You will find that Microsoft has provided a large number of training videos, articles, and support forums to help you get the most out of Movie Maker 2. You really get the feeling that Microsoft wants this product to sing. In addition to the Microsoft support, there is a host of companies and authors writing about Movie Maker 2. One of the most vocal goes by the moniker Papa John. You will want to check out his web site at http://www.papajohn.org.
Finally, Movie Maker 2 has all the power of Microsoft behind it. I am certain that the next release of Movie Maker will accompany the next release of Microsoft Windows Vista, expected in 2006. One of the criteria Bill Gates has outlined for Longhorn is better video support for solutions needed in the home. As a nation, we're taking to digital video (and controlling digital video) like ducks to water. Movie Maker must support this need or Microsoft will find that they have dropped the ball.