Check your emails. You might have a download code for the special demo waiting for you (requires a hell of a lot of blocks to download, though).
More or less the same as X and Y with some subtle differences here and there. It holds your hand through many of it and it's not really all that challenging. But it's only a demo, so you shouldn't expect much. It is, however, a good idea to keep that demo saved on your 3DS until you get the full game. You'll see why at the end.