It's interesting to see so many people say this isn't a Metal Gear game. I mean, other than the lack of cutscenes and relative lack/quality of bosses, this is as Metal Gear a game as any in the series. Are cutscenes what really defines what Metal Gear is to so many people?
That being said, it's interesting to juxtapose Metal Gear Solid IV and V. Both are divisive. They are almost opposites in that MGSIV is a short, linear, extremely heavily story/cutscene based game; whereas MGSV is vastly open, experimental, and light on story/cutscenes. While I believe MGSV is the better game, I will admit there was a catharsis from finishing MGSIV with its avalanche of nostalgia and straight up fanservice. With MGS V, while I actually do like the Chapter 1 story, there wasn't any catharsis at all. It was very cool and interesting, but I didn't feel closure. Considering this is almost certainly the last real Metal Gear Solid thing, that is a weird feeling.