I bought this game on March 20th, 2014 at 16:24
I will start with the problem. Ground Zeros is short. It is the main thing to say about the game. Even though this game only suppose to be a prologue for the main game (The Phantom Pain - TPP), you can barely understand anything from the plot and how it will be connencted to that game.
In the 70s, Snake is infiltrating a highly secured base in Cuba (Camp Omega) in order to resecue 2 prisoners and get away with him VIA a chopper. That's about it. There is a one cutscene at the beginning (Which, unfortunately we all have already seen many times before as the trailer of the game) and a shorter on at the end.
From this point on the plot ends and the 'Camp-Omega-As-A-Sandbox' side missions begins. Camp Omega is a pretty small area comparing to even 1 level of a typical Call Of Duty map but surprisingly, Kojima filled it with many little surprises there.
You can drive vehicles, interrogate for info on certain places and objects in the map (They still have to learn how to do this from Splinter Cell), observe and tag enemies with your binoculars.
The graphic of the game is impressive even though, personally, i wasn't amazed and expected more but that could be probably because i have PS3 and not PS4. The main new aspect of the game is that it's a free-world game. The map is very small but you can already be expecting for TPP to be amazing.
Kiefer Sutherland provides now the voice of Snake but he doesn't have too many texts (or anything to say frankly). Every side-op has a different mission giving you the opportunity to dig the map over and over again (some even on a daylight verision of the map) with various missions such as: killing everyone under amount of time, find stuff, destroy the AA guns and more. After you finish you will have the well known score.
There is so many things to do in this little camp so the replayability is something can be said as the real plus of the game as well as the new game mechanics that are teased here for the upcoming TPP.
To say if this game is worth buying, i am not sure unless you are a real fan of the series. Anyhow, this game can give you few hours to burn with its impressive challenges.