While I'm not quite sure yet how it will play yet, it can't be denied a mere 6 or so hr campaign is not a great way to cap off the trilogy of a big series like this. That's merely the typical made from movies type game length. I've also read that AI, both CELL and Ceph, can be easily taken out one after the other, because like clockwork they all investigate their fallen the same, making them easy prey.
I can see maybe one, or even two coming to take a look, but after a pile of corpses start building up, it's time to make the AI a bit less gullible. Too many games that have a stealth gameplay mechanic make this mistake. Look at Far Cry 3 for instance. You can use stealth, but you have to really earn it. When AI see a corpse their first reaction is to warn others, take cover, and investigate. If a lot have been killed they're more likely to take cover until they know where the threat is coming from, which makes sense.
