Fortunately, that's all I'll be comparing Charlotte to Angel Beats.
The story is quite mind-bending, albeit, a few scenes seem to be forced. I will however warn viewers who are incredibly family-oriented (such as me) to have a box of tissues nearby, because those moments really hit home. The story starts out slow but only because the information was needed to create a more logical conclusion. I won't mention how I felt about the ending.
The art is outstanding, as always. Every now and then, there would be unnecessary animation movement, but at the same time it shows some more depth.
The sound could use more attention for appropriate measures, but the music is phenomenal. Sound itself isn't a big factor in this anime, just the music.
Character design could be better. Most of the characters were not developed, and Nao's personality seems to be all over the place. One moment she's calm and collected, the next she's loud and quirky. Maybe it means something, but in the end it's a bit much.
Charlotte keeps you on your toes if you binge-watch. Despite some negativity, you shouldn't turn this anime away. It's always better to go into an anime unprepared than prepared for the best experience.
