Oh jeez. Now I find myself in the very difficult position of adding my viewpoint to 120+ posts talking about more or less the same, while attempting to add new information to something that's been commented over and over again. Anyway, here I go.
Foldable helmets: yeah, they're unpractical from a design point of view, BUT yeah, they're cool as hell. I personally think in the case of Dead Space 2 they stick especially out since, in my opinion, the suit's design makes the face section of the helmet something closer to a welding mask, in that it's a rigid, one-piece part of protective clothing. I think in DS's universe it would make a LOT more sense if the front section of the helmet just slid over the character's head. It could still be automated, it could still look cool, but you know, just add a hinge around the person's ear and let it move from front to top. Simple, elegant, and credible for the even bitchier fan. When on top it would still offer protection to ANYWHERE except the face (that is, top and back of the head) if that's the user's will. Want to have all your head exposed? Then take it off. I think that'd be the best option, while still looking cool and sci-fi and being convenient and shit. But the multiple-piece animation looks way cooler and it's still the future, so yeah: it's something we'll have to accept, same as explosions/thrusters noises in space.
Now, I'd like to stand out for something I hold very dear while on the subject: Mass Effect. I don't quite remember if that happens in Mass Effect 2, but at least on 1 the helmet comes off from virtually nowhere, which would stick out as another fairly unrealistic plot device, BUT: This game revolves around mass effect fields, which is the techno-magic used to explain a lot of the unrealistic tropes in that universe. Mass Effect makes everything lighter or heavier, which would explain that disappearing helmet: it just folds and goes unnoticed (still, it doesn't explain a 150+ item space), but hey: helmets don't need to be protective because there is an energy barrier that wards off kinetic hazards, so the helmet could be perfectly made of ultra-light alloys only designed to be hermetic, so there's that. I know Yahtzee didn't even mention that, but damn I'll show my ME fanboyism if I have the opportunity to do so.
And about the lack of human-like emotions to enemies: I think that's just lazy. In my opinion if you make everything look painful, bizarre, gorey and most importantly, if you make it happen SLOWLY, that'll be hella lot more unnerving and scary. But the game seems almost absurdly focused on showing Isaac's inner turmoil, and almost all of the horror is concentrated on making us fear for the character's safety. Which is cool, I guess, but doesn't even bother on showing us much of what happens when you turn into a monster. So the game is more "don't let me die to these non-descript things" instead of "I'M FACING ONE OF THE GALAXY'S MOST TERRIBLE HORRORS -also don't let me die while doing it". But again, that would require the game to radically change its focus and turn it into something more similar to a coral documentary about the necromorphs instead of a single person's adventure against the monsters. So it's the plot's natural trajectory and is more than expected, I guess.
So there. It isn't really a surprise to me, since I kinda felt the same way after the first Dead Space, but I thought it was something that could be improved towards a second installment: we already learned to fear the creatures, now we could feast in the bigger-than-the-universe horror and how it predates on humans OR in Isaac's personal demons. It still feels like it chose the wrong path to me.