The appearance of Master Chief’s face will still be kept a secret as he won’t be taking his helmet off in Halo 5: Guardians.
A recent interview with Tim Longo who is the creative director for Halo 5: Guardians asked him if Master Chief will finally reveal his full face.
Longo wasn’t sure if he was allowed to say anything, but he confirmed that Master Chief “doesn’t take his helmet off“. His appearance will still be kept a secret. You won’t see what John-117 actually looks like.
Bungie initially wanted to keep Master Chief’s face a secret so players get the illusion that “they” are the character himself. Not to mention the character’s aura might change if people know more about what he looks like.
Some people feel Darth Vader’s aura was ruined when George Lucas made the prequels. It didn’t help that he was only a kid in Episode 1 and was played by Hayden Christensen in the other two episodes.
I feel 343 Industries should keep his face hidden. Master Chief might lose some of his coolness if his appearance doesn’t match how players think he looks like. You also lose that illusion that you yourself are the Master Chief.