Following the leaked in-game shots from Halo 4 earlier today, the embargo has been lifted and you can take a look at the dev diary and gameplay below:
Halo 4 picks up directly after the events of Halo 3, and will focus more on Master Chief and expanding on his character. This would explain why 343 have gone with a more cinematic approach to the game. Another interesting point is the new audio team that are building all of the audio from scratch. Make sure you watch the video for more details!