It's a desktop client (available for Windows only), and you can also post to it via e-mail or SMS. It gathers local news from 20,000 sources and displays it on a map. It lets you post alerts (short messages) and reports (longer posts). Finally, it integrates with Facebook, while Twitter integration will be added at a later date.
Vine's biggest problem is that it competes with Twitter and Facebook. The fact that it offers a slightly more structured way to communicate might not mean much to the end users; they're used to getting their emergency news and reports from Twitter, even if it only means simple 140-character messages. And yes, Vine promises robustness (the details on how, exactly, are sketchy), and Twitter has long been notorious for its instability (it's working much better lately, though). Even if Twitter is down, however, Facebook's status update can always step in. Is there room for another contender?