If you are familiar with shoujo manga, then you will genuinely laugh at the tongue-in-cheek approach of this one.
Tonari no Kaibutsu-kun (or My Little Monster, as I first knew it) is my favorite shoujo manga. I loved it so much that I felt obligated to purchase the whole series in hard-copy form after having completed it, so that I could read it again and support the author. It's different.
What sets it apart in my mind is the humor. The author caught me off-guard so many times throughout the series. The scene would be set for a stereotypical, sparkly shoujo moment (e.g. compromising positions! the first kiss!)--and then something completely unexpected would happen and cause me to literally laugh out loud. Both character's lack of social graces largely contribute to this, although it looks different for each.
As I have become more familiar with the shoujo genre, I can't say that the lead characters (as much as I love them) are particularly unique. Shizuku is quiet, cold, and studious; Haru is handsome, spontaneous, and inexplicably talented. Even their relationship is a bit of a trope (the initial attraction between the parties is fairly out-of-character).
The supporting cast, on the other hand, is very strong. Their lives outside of the main story line are well-defined, which is uncommon for shoujo. The most surprising thing is the love rival, Yamaken. Love rivals in shoujo usually come in one of two forms: the long-suffering companion who has waited to stake their claim, or the sly "devil's advocate" who has no foundation for their attraction. Yamaken is not particularly likable, but as his character progresses you grow to truly appreciate his unexpected love for and friendship with Shizuku.