I'm most excited for Phantom Pain because the template for semi open ended gameplay with a strong set of character control was proved with Ground Zeroes. I love the idea of a game that feels distinctly Metal Gear in play yet offers a wider play space and cohesion between areas than previous Metal Gear games, all of which have been small in sized and partitioned behind area zoning. Ground Zeroes felt proper open, even with obvious objective locations bottlenecking you, as movement between areas had a strong sense of agency and freedom. That TPP is basically built around this idea is exciting to me, as it's still Metal Gear but something quite different and a logical evolution of the game design.
But I'm not without concerns too. The open world, though we've seen little, looks pretty boring to me with a lot of large, unused, and potentially useless playspace that also doesn't look particularly good. The footage shown has TPP look distinctly cross generation, lacking the scene density and convincingness of something like Wild Hunt, which too hard large stretches of nothing but managed to render them at high detail. TPP looks a bit empty and asset repetitive by comparison, which I guess is to be expected, as this is not a true current gen game unlike Witcher. So a part of me does worry that the choice to go open world wont be truly necessary in the long run, when they could have gone for a pacing similar to the past games only with much large and cohesive place spaces as evident in Ground Zeroes. Like a whole bunch of Ground Zeroes linked together through narrative.
I'm also a bit worried about Mother Base, largely because I feel RPG/stat systems don't have a place in action driven games like Metal Gear, but I remain optimistic because it looks better implemented than Peace Walker.
Narrative I'm neither here nor there. The story has long since gone off the deep. As long as it has its moments, very Metal Gear, I'm good.