Argentina has been the biggest surprise so far. I though they'd be one of the favorites, but their game has been awful. Hard to tell what they're even trying to do, no-one in midfiled to build-up play unless Messi drops deep and then there's glaring holes in the attack. They couldn't move the ball to stretch Mexico's defence until a moment of magic by the maestro. Hope they'll improve soon.
I'm rooting for Netherlands as I've been doing since 1994, but they are pretty lame these days. Doesn't resemble the Dutch football I grew up watching at all unfortunately.