I know that a lot of people who used previous versions of iMovie don't like iMovie '08, but as someone just getting started in creating and editing videos, I find it to be very easy to use, and seems to work the way I think. Step 1, load my video files. Step 2, extract clips from existing videos to create the desired video, add effects, etc.
The library seems to work well as an organizational tool. Once I had my clips loaded I used the "skimming" feature to find what I wanted in my clips. Extracting clips was also a no-brainer. The UI is clean, and it runs pretty fast on my first-generation MacBook Pro.
After creating a short video from a collection of clips, I was able to export it without any problems. I just exported it to an MPEG-4 file, but there are other options to share content via YouTube, .Mac, and others.
Maybe as I use it more I'll find more features I wish it had, but at the moment I'm very happy with it.