Finally finished this, minus Quiet's ending and some other bits and bobs. But have completed Mission 46, "The Truth".
Safe to say I must have enjoyed something about it, or I wouldn't have put in 100+ hours. But there was also a huge amount of frustration, annoyance, and more grinding than your average MMO
The game does waste the player's time in many different ways, and I hate it for that. Making you return to the same location to do very slightly different versions of the same mission, four, five or six times to the same location.
The story is very thin on the ground and utterly unsatisfying, and I hate it for that. Most of the story was contained in the trailers, meaning we'd already seen most of the story cut-scenes before we'd even started
After watching many hours of cut-scenes in MGS3 and 4, and loving (mostly) every minute of them, this was a huge let-down.
The 2nd chapter is a complete mess, and the whole thing seems like it was hastily finished for a release deadline. It's jarring to be expected to replay old missions, and I'm sure this wouldn't have been a thing if Kojima had had more time. It smacks of last-minute desperation.
I'm not at all bothered by the twist ending. For some reason I didn't see it coming, despite how clearly the game signalled it with hindsight. And I'm not bothered that it doesn't bridge the gap between MGS3 and MGS1. What /does/ bother me is that as a self-contained story it is sorely lacking. The new characters are very weak. Visually interesting - yes, but beyond that they are lifeless. The Skulls are the least exciting enemy of the series, being essentially zombies. Skullface himself is barely fleshed out before he leaves; same with Eli. The way it ends - the final mission - is a massive anti-climax. I can't think of a worse final mission, tbh.
So now I'm just left asking myself why I didn't quit after the first 40 hours. I should have. I kept willing the game to turn into a Metal Gear game, but it never does. As someone else said, "MGS5 is the best Far Cry game yet." But it's overly-long, repetitive, frustrating, boring, bland and disastrous at the same time.
I want those 150 hours back