I think Bob and phelt have hit the nail on the head, and I like phelts quote in particular. The organisational features and the all-in-one nature of MC are its main strengths for me, and I think that should come across up front.
Heres a blurb to illustrate. It will be obvious that Im no advertising copywriter, but it was a fun exercise for a Sunday morning.
Organise your media your way. Want to arrange your pictures by subject, date, and location? Categorise your music by artist, album, genre and assign a star-rating to your favourite songs? Or sort your videos by director, cast and year? Do it easily with the most powerful, flexible media library there is. You can add as many custom categories as you want.
Play your media your way. Create a slideshow of your holiday snaps, and add a music soundtrack from your song library. Get the party started with a playlist of hot tunes. Or let MC do the work with an Auto Smartlist. An hour of random music, a CD of MP3 favorites, an audio CD of recently played tracks. This and more are what "Auto Smartlists" are about.
Integrate your media into your life. Copy music from MC onto your portable digital audio player. Make a CD of music for your car. Record your favourite shows with MC and watch them on your TV. Got more than one soundcard? Play different music simltaneously in different rooms, or the same playlist from every speaker. Use Media Server to stream your music to your PC at work.