Ubisoft confirmed the news today on its official blog, stating that what many saw as one of the most exciting next-generation launch titles has been delayed until Spring 2014.
As for the reasoning, it’s because Ubisoft didn’t think the game would be polished enough (ie they need more time):
… from the beginning, we have adopted the attitude that we will not compromise on quality. As we got closer to release, as all the pieces of the puzzle were falling into place in our last push before completion, it became clear to us that we needed to take the extra time to polish and fine tune each detail so we can deliver a truly memorable and exceptional experience.
In related news if you pre-ordered an Amazon PS4 bundle with Watch Dogs included then this will NOT delay the shipping of your console in November. You will still get it on time.
Don't worry if you pre-ordered the Watch Dogs PS4 bundle, you will still be getting your PS4 based on your current delivery estimate.
— Amazon Video Games (@amazongames) October 15, 2013