He has literally zero personality. There’s nothing original about the completely silent protagonist and it just feels awkward in some conversations. I see a lot of obsession around Rookie and Noble 6 on social media. I get Noble 6 because he/she was customizable and felt like a placeholder for the player. Rookie, on the other hand, felt like a mute robot. Though I do admit I really liked playing as Rookie in Mombasa Streets.
The Rookie isn’t really a character, because the Rookie is you. Noble 6 has voice lines, but the Rookie doesn’t. There are no canon thoughts from the “character”. It’s all about what you think about the situations you (“The Rookie”) are placed in. Think of it as an abstract Virtual Reality concept.