From what I've seen, every chunnin shown (especially the sound and sand chunnins in the Konoha war) has been killed like foot soldiers. Mizuki sucked, Naruto (an academy student then), kicked his ass using a jounin level kage bushin, a jutsu that other gennins (Sasuke, Lee, Neji, Kiba) could counter/handle. Iruka is just as worthless as he was almost killed by Mizuki.

None of the Chunnins besides Shikamaru is shown to have any special abilities. All they do is fight taijutsu style and get their asses kicked by Kakashi and Gai.

The fights shown between the gennin team and the sound four looks like elite jounin level battles, compared to chunnin battles.