My hope for an anime is that it will keep me entertained. Charlotte did that. There is enough tension and conflict for it to keep you hooked. Still, I can't say it's good. And before I go into that, let me warn that this will be spoiler territory.
The story feels badly structured and it somewhat crumbles in the end. We have a random character who shows up, the protagonist's older brother. Due to various plot-related reasons, no one remembered him. And I should mention I am not talking about the audience but rather the characters. No character knew who he was, and we as the audience probably also forgot -- while he was still on-screen. We had gotten a couple hints but when he finally appears it is very underwhelming. You can't really get attached to him. And, worse yet, so much of the later story's development is dependent on this character.
Some plot threads and what seemed to have been Chekov guns go nowhere. There is a whole episode where a blind singer implies that the protagonist may go blind himself once he "makes a difficult choice" or something like that. That moment feels like it's setting up for some future hardship of the protagonist's part but it never materializes. On the one hand, the lost older brother does lose his eyesight... but these two concepts were never well married. And that's a single example of this sort of issue, of foreshadowing that amounts to very little.
Also, in the very last episode the protagonist turns into a killing machine. And then... that... suddenly gets resolved? And... everyone is happy? Strange.
I will say, however, that the ride was not bad. It keeps you guessing for most of it and there are some nice character moments. I especially liked the friendship between the protagonist and the glasses dude. It will just not leave you all the way satisfied, so to speak. I would still recommend it though, especially for someone more seasoned with anime, or someone who can overlook some anime tropes - maybe through Stockholm syndrome, as we are eventually prone to develop. I, for one, hate to admit that I have grown to enjoy those high-pitched anime girl voices.
Yeah, I may have to take this one to the grave.
Basically, the anime could not pull off what it was setting up to do. But it was still worth it.