One of our clients went with a card-based approach (http://purelyapp.com). The reasons were:

- People understand them. The separation and spacing lead to very little cognitive overhead.
- Perfect for responsive layouts, and translate easily to native mobile devices.
- Forces you to discriminate - you can't cram too much information in a card (at some point it ceases being a card), so it provides a nice constraint and keeps your product simpler.
- Easier to A/B test. Cards are a great example of what Andrew Chen has called an 'open system'. Many layouts are just loops of cards, which means making changes to a card object is trivial vs. changing the layout of a less modular, more structured page.

Hope that helps!