Here's my opinion, for anyone who cares after 5 pages:
I played many so-called controversial Games, like Manhunt or the Columbine thing, and had no qualms with it...but this crosses a line for me.
Why? Because not only the game wants you to do something disgusting, but because it MAKES NO SENSE!
Of course, i haven't played the full game and that one might provide enough context to rethink my opinion, but as i see it, that is just something that wants to show you how evil the evil guys are...by making you one of them.
That might be actually something interesting and deep if it is woven in the story narrative in a way that the terrorist are made sympathetic until this point where you just slaughter innocents, but as a standalone chapter, that is just controversy for controversy's sake. I can't blame anyone misunderstanding the purpose of that sequence because, in the end, this is essentially a terrorist sim.
Until Infinity Ward, through the game, cannot answer me the following questions, i consider this opening dumb and disgusting, and won't, for the first time ever, play this game despite wanting it due to morale issues:
1) Why can't this chapter be played through the eyes of one of the civilians, running away without a chance to fight back, and eventually get killed at the end?
THAT would show MUCH better what makes your enemies something that must be stopped.
2) How are you supposed to really want to fight the bad guys through a "emotional" motivation if you first play one and then just "change team"?
3) And most importantly: How do such mature and dark themes weave into a game that is essentially MICHAEL BAY'S WAR!! and puts you later in very hollywood-esque snowmobile chases and lacks overall real depth?? (not that this is a bad thing, but it just does not fit with the things shown in the opening)