I'm in two minds about this game - on the one hand it offers fantastic gameplay that you could play for hours but the story is absolutely lackluster and almost non-existent which is shocking for an MGS game. It's very much a mission-based open world game and not a narrative-driven experience that you'd expect from the series. The missions are fun but it can get very repetitive. The story is exceptionally weak, the script is abysmal and there isn't much variation in the missions on offer. Having said that; you could easily get 100 hours + out of it especially with the base/weapons/items development but it can feel a bit tedious at times. There is 50 missions in the main 'story' which is bullshit as only about 12 are regarding the plot - the rest are just side missions practically and we already have 157 of those. Chapter 2 is an insult because most of those missions are just repeated from the first chapter but on a harder difficulty setting - this is one of the biggest design flaws I have ever seen in a videogame and it's a travesty that it's come from Kojima - he's filling in the plot holes by recycling and this just makes the absent story seem cringeworthy. Also the game feels unfinished and there's so many plot holes and filler moments; it's actually quite embarrassing to play at times and you have to wonder what brands of cigarettes they have in Japan as I don't know what the fuck Kojima and his team was smoking at the time when they were designing/writing this game.
On the whole, it's a great game in its own right and you will get your money's worth but as a Metal Gear Solid title; it's one of the weaker ones and the way it was produced is mortifying.