Most of the characters are bland and vaguely stereotypical (and I've heard arguments for the fact that they are SO stereotypical because they are trying to subvert those archetypes, which I... well, don't really buy), and the humor itself is either playing on those characters' "quirky" personality or referencing other animes, both of which I don't find to be done in a particularly interesting way.
To top that I find Haruhi's character and what she turns out to be very... off-putting, as it tries in some form to subvert the manic pixie dream girl trope but somehow ends up with an even worse character by doing so.
I will assume this is a series that can be a lot more enjoyable for people who are really into the whole otaku culture thing, as they will probably will be far more receptive to the constant parodying of anime genres and situations. Personally I found it a bundle of interesting ideas brought down by its own niche appeal.
