I was pretty much convinced that the Pandorica was either a prison for this doctor or had a future doctor inside it because he had gone insane and decided to destroy the universe from about half way in, mainly due to the question the Doctor himself presented, why would every one of the universes most powerful and at times evil races show up at the same time? The only thing they have in common is the Doctor.
I must admit I really loved the ending, the most evil races in the universe working together to STOP the Doctor, not because they just want rid of him but because they feel HE is the greatest threat to the universe, utterly genius.