First-person narration is a technique that allows the reader to get inside the narrator-character's head. It lends psychological immediacy and interest to a story. We can follow all the character's thoughts, see why they act as they do. In this novel, we share all Ponyboy's emotions and hopes and fears, we can find it easier to sympathise with him as we follow his story. First-person narration can also allow the author to depart from standard language use in the writing of his or her story and adopt a more distinctive style. Here, Ponyboy as narrator sprinkles the text with his own colourful use of youthful slang. This makes the story stand out more.
At the same time, we should also be aware of the drawbacks of first-person technique; for instance, it means that we are essentially limited to the perspective of one character.
The benefits of Ponyboy as the narrator all comes down to the thoughts of Ponyboy. The book is told by Pony so we'll be able to know his thoughts about things, which is good because we would be able to know him better. On the other hand we'll get to know less about the other characters like, Johnny, Dally, Darry, Cherry, Two-Bit, Steve, and Soda'Pop. Since the book is told in a first person way, we get the beginning and the ending of the book which makes the book very special. Basically the ending is similar or exact to the beginning. The whole book is his essay and how he expresses and feels about it. The book has to be written in a first person mode or the ending wouldn't make sense.
Benefits: We get the good ending, we get to know Pony more, and his expression and feelings.
Cons: We get to know less about the other characters [Johnny, Dally, Darry, Cherry, Two-Bit, Steve, and Soda'Pop]