Congrats on the raise :)
I just tried Prismatic, and while it seems interesting I don't think I would become a regular user. Though I may not the target audience.
I'm usually satisfied with Hacker News and The NY Times, though occasionally I'll look at other mainstream news sites like CNN to make sure that I'm getting a well rounded idea of what's going on in the world. I have Reddit blocked on my computer, but I'll look at it on my phone for comedy & interesting news.
After integrating with Facebook and Gmail, these are my current Prismatic headlines:
* The Huffington Post: Release Of Cult Sandwich Slated For Dec. 17, McDonald's Announces (Bad)
* RollingStone: On the Charts: Alicia Keys' 'Girl on Fire' Leads Lukewarm Week (Bad)
* Webmonkey: A Look at the Future of CSS (Okay)
* Complex.com: Inside Johnny Depp's New $17.5 Million Home in Nashville, Tennessee (Really bad)
* Skysports: Graeme Smith determined South Africa maintain momentum against New Zealand (Really bad)
The problem I see is that (a) my Facebook likes aren't necessarily representative of what I want to read about, and (b) even if they were, your system doesn't know what priority to give each like.
The result looks to me like a page full of linkbait. My experience may not be representative, but I thought I'd share it with you as it might be helpful in fine tuning your product.