Let me break this down.
Main girl is trapped in a tower. Main girl runs around for a bit, before meeting this scythe-wielding lunatic, who has a fixation for seeing people smile before he kills them. Main girl's expression is blank. They join forces with the promise that scythe guy is going to kill her after they escape. The two scurry around a bit and meet bosses on each level of the tower, who all want to kill the girl. They try to find a way out. That's it. That's the plot.

Pros:

• The animation. God - no, I swear not like that - the animation. Everything about it was spellbinding, but not because it was super dynamic or had some insane anime fights. The imagery was really pretty, and even though you can probably find a dozen reviews calling it out on the wrong religious Bible themes, the animation still gives you a vibe. The church was one of my favorites to see, and the representations of different types of gases... There's a lot of gore, so be wary if you have fragile eyes, but the way they used "pure" colors like white in contrast was really nice. If you want a taste of the animation style, watch the opening.
• The antagonists. Okay, so they weren't the most dynamic, or didn't have too much backstory (at least in the anime), but the antagonists really hit. They were all yanderes minus the romance, and yeah, I found that cool to watch. Eddie's design with the potato sack, the reporter girl with her sick tendencies, and the doctor gave me serious chills. I'm never looking at the word "peepers" the same way.
• The plot. It was decent - your standard: let's escape from here. Still, though, if you want to watch children suffering, there's a better way than watching Angels of Death.
• The voice acting. Both English and Japanese. A little quiet on Rachel for English, but she really pulled off a soft voice that made me uncomfortable. Zack's is...it felt in-character, let's just say that. In Japanese, it's just your typical quiet anime girl's voice (which is perfectly fine) and Bakugou Katsuki. Take what you will from that.

Cons:
A lot.
credits roll
Okay, okay.
(Mild Spoilers)

• The dynamic between main girl, Rachel, and the scythe guy, Zack. One thing is for certain in this anime, it was trying way too hard to be edgy. I get that it exists in the real world, but Rachel wanting to die - but only through Zack's doing was way too on-the-nose. Keep in mind that Zack is a scythe-wielding psychopath, who Rachel just met, like, two hours ago. Wanting-to-die-from-them at first sight, much? Then later, after a few episodes, Rachel's downright obsessed with Zack, calling him a God. This is something I just don't get. In the beginning of this anime, their relationship screamed "abuser-victim." Then in the middle, I started to get vibes of two mentally-unstable siblings.

At the end?
How do you go from please-kill-me to you're-my-God? Seriously, the first part of it was already weird and unbelievable enough, but toss in the latter? The metaphor doesn't even work because practically no one asks their God to kill them.
And the last scene... The goddamn last scene. What was that?
This whole time I knew Rachel's sole and only motive: to be killed by Zack. I knew Zack's sole and only motive: to get out of the tower and kill to make himself feel good. But I knew there was a dynamic change in these two characters - how did the last scene just end up bringing us back to the first episode? Seriously, did I spend sixteen episodes for nothing? (Yes, yes, you did.)

• The...rest of the plot. I suffered through sixteen episodes about two psychopaths (plus their psychopathic bosses) in a tower trying to get out, full of Christian allegories, and yet...I don't even get a clear answer on anything. The world these two were in was built on the basis of metaphorical toothpicks. Worldbuilding, never heard of her.

At first, I thought this was some sort of hell, and Rachel had died from suicide (there was a brief shadow hanging, which I was sure was Rachel, in the opening. The suicide would also explain why she was unwilling to take her own life again). But the plot was so topsy-turvy that I felt so confused on what I was watching. I still have no idea what that tower was. Was there some sort of magic that gave everyone serious wound-immunity? How did Rachel get into the tower?
I have no idea who did the target audience this show was out to hit, and I genuinely do not care about finding out. At times, it had creepy psychological aspects, then fun video-game levels, then weird God metaphors, then sad background stories™, then "O Zack, O Zack, please kill me." On a more serious note, I find it so weird how Rachel is pretty much tortured the entire time - this thirteen-year-old girl hasn't caught a break once . Let that sink in.

• The plot twist that never came. I expected a plot twist, and I seriously didn't get one. I got a music box, sewing, a Maze Runner-esque escape, a therapist lady, and an open ending. Are you kidding me? I think the whole lead-in to Rachel killing her abusive father was way too dramatized. When did Rachel lie about it? I think practically everyone who watched Angels of Death knew Rachel wasn't innocent, and she probably had blood on her hands pre-Tower Era. Even though the sewing part was really interesting, it didn't fit in the anime - it felt like the background story of another anime character, because Angels of Death doesn't get the chance to flesh out its characters in the beginning, so there's really no point in throwing in a half-written background story as a "twist." If that open ending was a twist, you must be out of your mind - that open ending was hardly even open.

Final Thoughts
This anime wasn't horrible. Do I regret every second I spent on it? Well, um, yes. Do I wish I could've smacked my past self at wasting my time? Yes. Am I sure there's someone out there who'll enjoy it? Yes. Will most Christians enjoy it? ...Er, no, but you guys should check it out for an r/mildlyinfuriating substitute.
Still, I liked it. It was pretty and superficial and skin-deep, but maybe that's the beauty of it. It was like one of those unfinished, half-done drafts that I'd never recommend because not only is it bad, but it doesn't feel complete. If you want to enjoy this anime - watch all the way until Catherine's arc, then headcanon the rest. Trust me, you'll save time and energy spent on a lackluster, edgy, it's-not-a-phase-Mom anime.