Very beautiful portrayal of dissociative identity disorder (some minor mistakes, like "creation" of alters, it sounds like Elliot had to choose how they looked, what they did, that's not how it works (the Christa INSIDE Eliott's mind phrased it that way, so it was based on Elliott's knowledge, but anyway), I would recommend researching this disorder and learning about it before watching the series, as it will help you understand what's going on), I liked that he wasn't portrayed as a monster, or having a superpower (if you watched the Split, you know what I'm talking about), because people with DID are horribly traumatized people, who are struggling their whole life to live normally.
THE MUSIC... I usually ignore music and sound effects in movies, but here it goes so perfect with every scene that you SEE the sounds and HEAR the visuals, so incredibly done.
THE VISUALS... Even if you ignore the storyline and music THE VISUALS are something else, I loved the camera work, transitions, color correction..
SPOILER ALERT
and the ending... so heart breaking but good, no cliche, the ending left me so satisfied.
oh and I wanna say something about one episode, that episode starts with "If you don't wanna talk, I'm okay with it" and end with "it's time we talk" and NO VERBAL INTERACTION IN BETWEEN. But that episode had me stick to the screen like I fell in gorilla glue then on the screen hahah, It was so full of intriguing moments, feelings, worries that you don't even notice nobody says a word.