I really enjoyed the 2012, for the most part. I thought that the special effects were amazing, and the unfolding of the story (writing) was well executed. I cared whether or not most of the actors/characters survived.
On the downside, this movie was about 30 minutes too long. I understand setting up the crisis quickly and answering questions as we go along, but the pacing was so nice at the beginning. To slow down so much as the story progressed killed the energy of the film, and caused me to care a little less with every passing minute.
Though the entire cast was pretty exceptional and convincing all around, standout performances for me were: Blu Mankuma, Chiwetel Ejiofor, Oliver Platt, John Cusack, and Danny Glover.