About 8-10 hours is my sweet spot anyway, so 6-12 is generally fine too. Shorter and it starts feeling a bit light, longer and it always drags.
In between a list of games, movies, series, internet, a wife and child, work and friends all begging for my attention, long games just mean playing the same game for over a month and getting bored before the end anyway, so I would probably really like the length of this game. Lots of bang and then going on to the next game. It's just the bang itself that I'm a bit apprehensive about. Small corridor cover shooter sounds a bit dull, hopefully it takes us to diverse sceneries.