A great deal of virtual ink, which is nothing like actual ink save when used in a metaphor, has been spilled on the popularity of The Melancholy of Haruhi Suzumiya. It is fast becoming a sort of shibboleth, to identify those who have crossed the threshold to become a hardcore anime fan, by which I mean the sort to attend conventions and spend actual money on merchandise, official or otherwise. Like Neon Genesis Evangelion, whatever your feelings on the show itself, at least you have heard of it, especially if you actually do attend a convention. Also like NGE, it is probably not a very good first anime to introduce to the non-fan.
One of the many criticisms I have seen levelled at MoHS is that Haruhi is Not A Nice Person. From the viewpoint of a person watching the show for the first time, she's selfish, she's rude, she's arrogant, and her actions either border on or cross said border into anti-social personality disorder, depending on how charitable one is feeling. Yes, she gets better over time, but that does not change the truth-value of that descriptor at the beginning of the series, and from certain actions throughout.
The question is then posed: "how can you like a character like that?"
The answer I always give is "I don't." Which often requires me to clarify the differences between "don't like", "dislike", and "hate" (a matter of degree, with "don't like" meaning a mere lack of attraction). And then I am asked why I love the show when I don't like the main character, which kind of leads to a rather longer answer.