This game isn't a sandbox like Dragon Age... For a single player only game, if it takes like Murdered Soul Suspect or Ryse, up to 6,5 to complete, I'm okay with it.
Second Son take up to 10h to beat the game once and is a sandbox... Why are that 6~7~8h such a problem?
Should be games for all kinds, and short and intense ones are as good a 100+h games with lots of fillers.
The Uncharted games average time is also up to 9~10 hours... What if Uncharted 4 is jusr another 9h games?
That youtube 5,5h walktrough is clearly rushed and played on easy just to be the first uploading a walktrough of the game to get views... I don't see it taken less than 9h playing on hard and exploring the enviroments.