My incomplete list:
1. Simple multi-track editing and compositing. Way better than iMovie.
2. Titles can be generated with Inkscape in SVG format. Way better than Final Cut.
3. Plays nice with all the media file-types that I care about.
4. Theme-able. I’m not a fan of the default glass theme.
5. It’s the perfect companion to my new Zi8 camera.
I’m sure I’ll find more to love as I produce more projects.