What is my problem with "Ils?" Well, it does maintain tension throughout it -- that is without dispute, but the kinetic nature of it, some of the protagonists' choices, this "scared rabbit" mentality they had, it spoke to a kind of political slant in the view of the writers, I think. A kind of moral message carved into the story with a butcher knife, which isn't particularly what one needs in a slasher movie.
So, why did "The Strangers" hit me harder than "Ils?" I think the sense of home invasion was stronger in the former than the latter, and the dilapidation of the simply massive dwelling in "Ils" made it, paradoxically enough, less threatening than the nice cottage of "The Strangers." You already expect horrors in the "Ils" dwelling -- the place looks like the playground of an undead Bond villain, whereas the dwelling in "The Strangers" is a nice, cozy little home -- so, when the descent into nightmare is undertaken, the fall is further in the American version, most definitely.
The protagonists in the American version are somewhat more savvy (and combative) than the chickenshits in the French one. I think any American watching it would be like "C'mon! Deck'em!" when confronted by something like that.
Similarly, the villains in the American version are both more visible and less human than the villains in the French version. There's something terribly chilling about the Mansonian wackos with the masks (see below), when contrasted with the hoodie-wearing villains in "Ils." There are only three killers in "The Strangers" and there are many more in "Ils" and yet the three baddies in the former are far more terrifying.
The use of silence, music, and noise in the American version cannot be overstated -- it plays a key role in it in a way that the French version lacks. The French have you careening through the cavernous dwelling when the American version has you sitting there, in darkness and silence, waiting -- much more powerful stuff. Even simple things like hard knocking on a door at odd hours is absolutely terrifying in "The Strangers."
Perhaps the civilization of the French accounts for the horror they perceive in the "big reveal" of the story, whereas, in the States, where all sorts of outrages are apparently more common (or we hear about them more), the reveal is kind of not so revealing. Oh! Good heavens! Versus in the American version, the baddies are big and bad and scary (and two of them are girls) and we ultimately don't know their identities, and something about that makes it scarier -- we don't know who they are, and their motive for doing it is simply because the characters happened to be home. The arbitrary and absolute nature of that violence seems more terrifying to me than the moral outrage we're supposed to feel in "Ils." Maybe I'm jaded.
I'm at a loss for why "The Strangers" is less-favorably reviewed than "Ils," because I'm a fan of French filmmaking, and I really wanted "Ils" to deliver for me, but it just didn't. Tense, yes, but not terrifying. I think people feel like maybe they're supposed to like the original better, but in this case, I think the American remake was superior. Maybe it was in the hands of a better director and writer, I'm not entirely sure, but one terrified me, and the other didn't.
I'm forever grateful that "The Strangers" came out a few years after I'd sold my home in the quiet woods! Even then, I found myself being sure the door was locked in the apartment while watching it. "Ils" didn't spark nearly that same reaction.
