I am at like 27% of the game completion, and I have done tons of side ops ...some even multiple times for GMP and materials. This game has its moments, the variety in which you can complete the missions is just amazing. Go past everything or go rip apart everything. Not only that the variety in the main missions is commendable as well.
Last mission I did was the Rescue Shabani mission, the mist valley reminded me of The Sorrow encounter I was like feeling that some spooking bastard of a boss is gonna jump out of the mist, then you proceed towards that cave which leads to that massacre site, holy shit that was some intense shit.
The complains about the world being to huge and bland, well this is no RPG or anything that you'll meet random NPCs scattered around the place. There is a thing called game design philosophy and developers ambition to go into depths to implement their vision in the most perfect sense. People should learn to appreciate such finesse, in an era cluttered with recycled content.
I have no complains about the world being too huge and bland, the game design philosophy is just perfect. I have been following Kojima since the days of MGS1, and he has always emphasized on creating a open world infiltration game. This is not open world just for the sake of being an open world, this was his vision which he implemented as he always wanted.
BTW I did that Traitors Caravan mission and got an S rank, what I did was used those tanks to kill the skulls, took me a few attempts but when I did it ... I S'ed it.