I got into anime in my late teens and this was the one that really hooked me into the hobby. Dressing up as Haruhi, buying the manga, etc. It has a sister anime called Lucky Star that aired along side it. They would reference each other a bunch.

The endless eight almost killed it for me. If you want to spare yourself the first and last two should be more than enough. Or better yet read the endless eight instead. It was done much better in print.