The idea isn't particularly unique and it wasn't particularly well executed when the first version was built but with the investment he was able to hire some talented people and from what I've seen the application (as is available now) is excellent, however it seems that he is now primarily their advertising vehicle. He's being used to market the app and it's certainly working, it's getting them huge amounts of press compared to the other companies in the same space.

Stephen Fry is in the advertisement video for Summly, he tweeted it to his ~5 million followers: https://twitter.com/stephenfry/status/264066858225905664

The Summly team: http://summly.com/about.html

edit: oh apparently Stephen Fry is an investor, that explains the "free" video.

edit edit: I wonder how he feels about his age being such a huge part of the stories now, back in August 2011 he said this:

    So he kept it under wraps. "It was a conscious decision 
    to not disclose my age to Apple and the media," he says, 
    because he wanted "Trimit to be judged on its own merit, 
    and not the story of its creator being 15." 

From: http://www.fastcompany.com/1772823/15-year-old-creator-trimi...