To start off the discussion, I’d like to first say: I am extremely glad that she isn’t a Kanade clone! It’s great that she has not just some emotion, but quite a lot of emotion to her! So far, the only thing I’ve read are the first two chapters of the Charlotte 4-koma and in there, we get a glimpse of her personality: She is gluttonous, takes her works very seriously, but can’t help getting all excited and manic about things she loves (like food and ZHIEND). It’s really nice to see somebody with that sort of “genki” personality, but still manages to keep a level head. Ayane Sakura also gives a great personification to that manic personality, as I’ve seen from the ABC alarm app.
Character design is really great, too. I think her whole appearance jives well with her power. Her silver hair, for example, makes her feel very ghost-like, which is perfect considering her power. However, it’s the kind of ghostly feeling that you don’t necessarily feel afraid of; it’s the kind that draws you in and makes you even more curious about her.
tl;dr Nao is a really great character and has arguably the most personality out of all the Key heroines 
