Haruhi’s apparently a hipster.

Haruhi: “That was when I realized. If I went against the norm from the very beginning, I might end up having a lot more fun.”

Kyon(’s thoughts): “Your typical rebellious spirit would blindly shun anything mainstream and support the obscure, regardless of the benefit or lack thereof. (…) Still, I have a feeling that you could take things to such extremes that concepts like ‘mainstream’ no longer apply.” - The Rampage of Haruhi Suzumiya, page 166

Kyon on Haruhi Suzumiya.

"A whole plethora of words come to mind when discussing Haruhi Suzumiya, naturally, but if I had to describe her in a single sentence, it would go something like the following.

Here we have the last person in Japan who should be allowed near the launch mechanism of a nuclear missle.” — Kyon, “The Rampage of Haruhi Suzumiya” page 125

Koizumi on his role in the Haruhi Movie
Koizumi: "Actually I'd prefer it if my role in the movie didn't have too much dialogue. I know, why don't you take over the lead role for me?"
Kyon: "Haruhi's the one to talk to for casting changes. If you want to switch with me you should probably talk to her."
Koizumi: "Do you honestly think I'm capable of doing something so frightening?"