Alright. I finished it up about an hour ago. I think that user review makes some strong points about how the game works, but, where they saw it as a negative side of the game, I enjoyed all that stuff. There's really a lot you could say about the game, but I'll mostly leave it saying it's one of the most interesting games out there. It touches a lot of stuff gameplay, style, and theme wise (even more than previous Metal Gears). In the end it really does a lot to close the circle that started with Metal Gear Solid on the PSX, almost to the point of excessiveness and playing to fanboys. However, that's what Metal Gear is about, being excessive and revealing in it. I love it for that.
Having finished it, I'm leaving it with a rarely achieved completely satisfied feeling. It was a great ending and left me feeling a lot like the ending to the Lord of the Ring movies did; I turned off the system with that bittersweet feeling when something good comes to an end in an appropriate way. They knew the series tread a lot of ground and the world meant a lot to the fans. The game closed pretty much everything respectfully while reminding you why you loved the story so much to begin with.
And yes, it helped having replayed all the games recently, or even at all. I don't think it'll necessarily leave you wanting anything more than details in terms of information, but the impact of much of what is said and done is reliant on the experience of the previous events.
Edit: Oh yeah. And it if it isn't entirely obvious, this means I didn't really stop playing since I got the game yesterday morning. Once I started, I put in about 18 hours straight, got a few hours of sleep, and then played for about 6ish hours to "finish" everything up. That initial play session might actually be the single longest sitting I've done in front of a game, ever. If that isn't a ringing endorsement for a game, I don't know what it. Thank the gods for summer vacation (or what little of it I get).