Finished this last night. Love the atmosphere, sense of place, and the state of flux the environments have. The story obviously, great, with a cool, dark, twisted ending. The gameplay itself while slightly rote was well executed. Walker's compadres are limited in what they can do, but still they manage to throw a mean grenade, and the actual selection of targets works well. Cover works great, shooting feels nice, tight, accurate. Game looks fantastic on PC. I stick by my initial impression that this feels like a spiritual successor to Freedom Fighters, a game that had similarly traditional gameplay supplemented with great atmosphere.
On the bad side of things; the constant stream of deaths at chapter 14 got really obnoxious in a hurry, especially since sometimes forward progress felt more like it was based on reaching a certain geographic point on the map, rather than killing a preset number of baddies, which made it confusing/frustrating. Losing 20 minutes of checkpoint domination--arbitrarily--is never cool.
I thought it was longer than four hours, more like seven, I collected just over half the Intel, so definitely not rushing or taking my sweet-ass-time.
It is a "sum-of-its-parts" game for me, that really comes together in an effective and memorable way. Really think it deserves some higher reviews.