The value-prop isn't different. Stumbleupon has verified a market, but IMO they've failed to grow it to its full potential (along with google reader and netnews

The value-prop isn't different. Stumbleupon has verified a market, but IMO they've failed to grow it to its full potential (along with google reader and netnewswire). They've stagnated. They're failing to provide the most personalized experience possible. The readwarp solution is different from stumbleUpon. More textual analysis, more tight UI research, more integration with current recommendation sources like twitter and facebook. Less reliance on following random users based on a few links. I'm going after stumbleUpon. But this prototype isn't there yet.