jefequeso: I'm liking the HUDlessness so far. And I'm REALLY liking how limited your ammunition is.
Still not convinced by some survival elements, though. The gasmask system, for instance, just seems like window dressing. But I'm less than 2 hours in, so we'll see.
Xeely: The gasmask is quite annoying because the filter system is buggy, or just that bad. Basically, for some reason, you can't always pick all the filters you find on the map, you better buy them in the markets since they are cheap anyway.
The fact that you find a very ammount of ammo on the levels is nice, but if you (like me) are playing in the stealth way, you'll find yourself on the last mission having 500 military grade ammo or so. I mean, throwing knives for the win!
I've only been through the very first human/human firefight, and I found the stealth to be brutally unforgiving. And once you're seen, the enemies seem to develop super senses and can see you even if you're completely hidden in the dark. At least it seems that way. I did rather like how tense the fight ended up being, though. Limited ammo + only a few bullets need to kill you or NPCs = super fun times.
It's still going to take a lot to get me past my distaste for scripted linearity, though. And I'm not sure I'm happy with the fact that you're with another person all the time either. But again, only 2 hours in. So I'm witholding judgement as of yet.