High Jounin, he did beat kakuzu after all and he showed great intellect and analytical skills in that battle.High Chuunin. His intellect and analytical skills needs more polishing before he can go up the ranks.
After he had been weakened by the others. Even though Naruto was beaten up himself, he had to be saved by Yamato once before he landed the FRS blow to him. If he had faced him at full power, it would have been a completely different story. Overall, he just isn't as smart as any real jounin would be.High Jounin, he did beat kakuzu after all and he showed great intellect and analytical skills in that battle.