So I was browsing the web looking for info in MGSV TPP and according to people whom have already got the game, as well as users on Reddit and NeoGAF, It appears that Phantom Pains introduction sequence is about 1 hour long. This does not come as a surprise as Kojima loves to give long introductions into his games.
Reading a little further it's alleged to be an hour of intense and amazing cinematography as well as gamely.
