First person point of view is where the narrator is – usually – the main protagonist. It lends the story an immediacy that other formats don’t, since it details the events from that person’s viewpoint and experience. It can be a more intimate point of view, in that the writer conveys all the thoughts and feelings of that lead character to the reader. On the other hand, all the other characters are only seen from the protagonists viewpoint – as in reality. In reality we can only guess, or read/misread the thoughts and feelings of other characters, from their expressions and how they express themselves.
I chose – well, actually the muse chose – to write one particularly story from the first person POV for specific reasons. As a reviewer said, “This is a story that is real; maybe too real in some ways. I came to know the main character, and felt like I was present in everything she was going through in the story.”
That was and is the purpose of first person point of view – to make the story feel very real, to put you/the reader inside the protagonist’s skin so that you experience what they are experiencing. In a mystery, it allows the reader to unveil the clues along with the main character. It can also be used in other formats so that you immerse the reader in certain experiences.
If there is a mistake that many new or inexperienced writers make, it’s in prescience – “what the s/he didn’t know”… If they didn’t know, it’s not first person, it should be rewritten as third person, without the prescience. Unless they’re psychic, they can’t know. (And even psychics will tell you nothing is certain.)
Some readers don’t like first person so it’s best to let them know in what point of view the book was written. (In case they don’t look at the ‘Look inside the book’ feature.)
The Lovely Bones is written in a form of first person POV, but with an omniscient edge, since the main protagonist is dead but experiencing what is happening with her family. It’s a book I haven’t read because I’m too intimately acquainted with the protagonist’s experience. So I understand the readers point of view. Others clearly loved the book – it was a best seller.