This game is given so much unnecessary hate. It is a SPIN-OFF, not a direct sequel to any of the Metal Gear Solid games. It's like comparing apples to oranges...but yet people are mad because the orange doesn't taste like an apple.
The survival, building, crafting, combat, and even exploration mechanics are all entertaining and engaging. Additionally, co-op is incredibly fun when played with friends, and finalizing a strong build for online play is incredibly satisfying.
The story certainly leaves more to be desired, but the gameplay makes up for it. If I want a great story, I'll play the actual Metal Gear Solid series.