Just finished Peace Walker - the Main Ops story, at least, which includes Chapter 5. I still have a good handful of the Extra Ops to partake in.
First, it's gotta be said: this is the most difficult modern-day Metal Gear title I've ever played. The game's challenge teeters between richly satisfying to "Goddamn, this is a frustrating piece of shit." The stealth-based missions are all terrific - MGS3's gameplay style of 'slow and steady' carries over splendidly, enemy placement is smartly designed, and I love how you're forced to use all of your resources to get through. Planning the perfect stealth streak isn't just an option anymore, it's a necessity.
The action bits, unfortunately, don't fare as well. I despised those missions that require all-out shootouts. (Yes, I'm staring at you, Main Ops #24.) I never quite adapted to aiming with the face buttons with much efficiency, and the other control setups are no better. As such, precision shots in the heat of battle were an impossibility for me, resulting in harrowing deaths too numerous to count.
And then there's those vehicle boss battles. Pellasos mentioning that they get annoying after a while is an understatement: hell, I got fed up with them after the second one. They're a far cry from the inventive boss battles of Metal Gear titles past, amounting to little more than blasting the hell out of them with whatever missile-based weaponry you can scrape together. These things are monsters in the vitality department too; I can't believe some of them took me close to an hour to take down. Are these more tolerable when playing co-op? Perhaps, but for those without the luxury of playing multiplayer, better balancing should've gone toward the solo experience. I will say that the final battle against..... Peace Walker is spectacularly well done.
The story starts off slow, but picks up right around the time that Strangelove is introduced. The plot is still politically top-heavy, but once they've begun to reintroduce the intrigue of the MGS mythology, it once again becomes a gripping tale. It's gotta be tough for Kojima to keep the entirety of this story's timeline on the straight and narrow, and retconning around the definitively conclusive MGS4 is risky business. The bigger danger here is the expansion of (and potentially mucking around with) a story arch as beloved as The Boss'. The end result is a few story twists that made me go "WTF?" in a couple of places; reactions that obviously shouldn't be uncommon in this series, but still managed to catch me off guard given the source (MGS3) that it's drawing upon. At best, Peace Walker's ending shows far more restraint than MGS4's exhaustingly lofty finale, while being almost as potent as MGS3's in its brevity.
As someone who digs the Briefing Files in all the MGS games, the audio tapes and diaries are a dream. They're so insanely expansive, that I've yet to listen through all of them. I will say that the hidden ones are very much worth seeking out; they give amazing insight toward further character development.
I liked Kaz, and Strangelove ended up being one of my favorite characters. It's a shame Cecile became such a throwaway after her initial introduction, and I generally felt indifferent toward Amanda and Chico. (It is nice that the former gets something of a resolution by the end, though - that doesn't happen to any of the support cast in Metal Gear games too often.) There are naturally hints of Otacon in Huey, but Pops ain't quite Otacon. It seemed unnatural to hear him barking out the orders to destroy his AI abominations through the radio the way that he does.
And then there's this:
One thing I will say: I wish I could shoot Paz myself for her frequent and obnoxious ramblings about peace.
There are a lot of ramifications that can be deduced from this admittedly innocuous quip. We'll just leave it at that.