I spent almost 80 hours with MGSV and only have a 55% completion rate. It's easily my most played game in, shit i don't remember a game i spent more time with since i was in my teens. Even the last few final fantasies have only been around 40 hours long. I spent about 55 hours with Fallout 3 GOTY on the PS3 before the constant hard locks, framerate hitching, and just overall shittiness was so bad that i didn't even finish the last DLC I had left for it.
I agree with the general sentiment that Chapter 2 is kind of a mess but the game was so damn good 95% of the time that I can't give it too much shit for being a disorganized experience for that last bit. What a game.