There are 22 chapters in the game. I just started Chapter 21. So I know that by the time I go to bed tonight, unless for some reason I absolutely suck in one of the upcoming sections, I will have beaten this game. Then I'll be moving onto Crushing difficulty. Which I'm not actually looking forward to. It's more story driven than anything else, but some of the gun fights are kind of frustrating. Like the one on the plane, or one of them in a desert sandstorm that I just had to complete. Again, not overly hard, but the checkpoint is at a retarded spot.
It also has a nasty habit of taking away my weapons when entering a new chapter. Oh, sorry, you had an M9 with 120 ammo? Well, here's a silenced pistol with four bullets. Enjoy!
Also, I called the plot twist about fifteen chapters ago.