If this movie starred Dolph Lundgren and was written by the writers of Disney Channel sitcoms, I'd still recommend it just for the pure visual spectacle. Watching most of the world destroyed with such amazing effect was breathtaking.
That said, the storyline was a little weak. There was not much at all about the Mayan predictions of 2012. The characters weren't much to speak of. And the acting was a little spotty at times, although honestly I like John Cusack enough that I could probably watch him watching paint dry for a couple of hours.
It didn't have quite the emotional impact of Emmerich's Independence Day or even Day After Tomorrow. But it is still absolutely worth seeing.