Before I get this game, I've downloaded Ground Zeroes and I couldn't understand why Gamespot's reviewer gave it a 10, I had to check this out. The game is simply fantastic, parallel missions are entertaining, which means you never get tired of exploring the map searching for good soldiers to extract them to your base. You can upgrade everything, from your guns, logo, vehicles and even your horse (I am not even worried about rushing into the story mode yet).
You don't actually need to play the previous series to get involved in Phantom Pain. Konami (or Kojima) was able to innovate the series for the second time (MGRevengeance was the first innovation). There are a lot of possibilities and stuff that we could not find in the previous linear games from the MG series and that's probably the reason why this game has received a 10, while master-pieces like Batman did not (Batman is a master-piece for those who have never played the previous games).
I gave it a 9 and I will explain the reasons why: There's a not-realistic and inhuman side of MG series that really annoy me, which is scary, bizarre and sometimes macabre. Bulletproof fire-man riding a fire-horse., flying girl, super-speed soldiers and so on. I would love if the game kept focused on armies, soldiers and tatical stealth. Most of you probably like and enjoy this side of the game, but I don't and it's my personal opinion.
Thank you for reading.