I've heard mixed reactions about the series, including people who didn't like major plot twists and deviations from the original story. But honestly, I'm cool with that. Personally I like book-to-movie/series adaptations to be as close to the book as possible, but I'm also okay with some variations to keep it fresh and unpredictable. Even Jay Asher said he didn't mind the changes because the message of the story is the same.
And let me tell you that message will hit you HARD. Like a sucker punch to the heart.
As far as the characters are concerned, if you didn't like the character of Clay Jensen in the book (which is hard to imagine, but you never know), Dylan Minnette will make you fall in love with him, and Katherine Langford (who plays Hannah) is A-MAZ-ING. Langford brings Hannah's character to life in a way I didn't think possible. Like, my heart literally hurt for her as I watched each episode.
If you haven't read the book yet, I highly recommend you do. Don't worry... the library has plenty of copies.
Needless to say, this librarian's weekend will be booked re-binge watching the entire series.