And I loved it.
It was the zombie/horror version of 'Cloverfield', pure and simple. And since Cloverfield is one of my most favorite movies ever, it's pretty obvious this movie would appeal to me as well.
Scary as shit, no cliches, no cheese. (Nightmare t he 13th, anyone? No thanks. Not here.) Totally suspenseful, and immensely satisfying. They should have had a clever viral marketing campaign with this like they did with Cloverfield, because the two movies feel so similar.
If you like horror, and you liked Cloverfield, see this movie.
If you're curious, there's a Spanish version of "Quarantine" that came out last year called " [rec] ". Judging from the trailer I saw of Quarantine, the new one looks like it might be a shot for shot remake of the original.
If it's anything like [rec], I have no doubt that you really enjoyed it because we thought the Spanish one was great.