Okay, I promised to post my final impressions here, but I've been putting it off because it's all still sinking in.
I have to say that this is my new favorite visual novel. Now, I know people love comparing things to Steins;Gate because it's something a lot of people have experienced that's super high-quality. But, I'm going to get that out of the way first. They're very different types of stories, and they definitely have different strengths and weaknesses. But as an overall experience, Chaos;Child wins out for me. (And there's no question in my mind that it's significantly better than Steins;Gate 0, despite what the wrong-siders on Metacritic say.)
The common route is very well executed; despite its length it always feels like the either the plot is moving or the characters are significantly developing. The main exception is that the delusions are pretty much filler in most cases, but they're fun to experience in their own way (especially the negative ones). It feels like they just lifted the delusion mechanic from Chaos;Head without putting much effort into tying the delusions into the plot; however, they do provide more insight into the protagonist and their existence does have a purpose. Regardless, I found the common route an amazing ride from start to finish, especially piecing together the mystery and dealing with the consequences.
It slows down a bit after the common route, but each of the character routes tells its own story, and each one develops the game's major themes and characters, while having some nice twists of their own and introducing elements used in the true ending. Unlike some visual novels (I promised not to mention that one from earlier), they didn't feel so much like romantic options as much as exploring characters for whom these developments might have felt out-of-place in the common route. I'm still putting together my thoughts on the nature of the routes themselves, but that's a discussion for another time.
As for the true ending, I'm obviously not going to go that deeply into discussing it because of spoilers, but I'll just say that it still managed to surprise me after everything else, and its execution is just brilliant. I really wasn't expecting to feel as much for the characters as I did in the end, and I have to admit my eyes were sweating a few times. (That means crying, don't make me say it)
TL;DR, Chaos;Child is great. Probably my GOTY (though I admit my tastes are biased toward VNs and this series in particular).