Kiss is my favorite manga currently.
But in no way am I going to give a bias review so I'll be completely honest of my reasonings and the flaws.

First of all, when you first read the synopsis and start off the first pages you may think this is another one of those mangas-the stereotypical romance manga where two people are completely unaware of their love for each other until the very end, but Kiss is nothing like that at all.
Right from Chapter 1 and throughout the following volumes, Matsumoto emphasizes the struggles after struggles they go through, which is what makes me feel so interested when reading-not because of the drama, but because its realistic.
It is very realistic the issues they talk about and go through, which is why I feel such a connection with the manga.

I think this is Matsumoto's gift as a mangaka. Her artwork is not the best I've seen but the way she chooses the wording and shading, it makes a simple stare from the two protagonists have a deeper meaning and you can immediately feel the passion that the characters have.

I think the plot is pretty typical and common, but it is the characters that make me so fond of this manga. Matsumoto has a way of building up the personalities of her characters, which makes them appear, like I said before, REAL.
The way she subtly emphasizes their feelings makes the reader think about the true meaning of the words and the expressions.
I feel like I know the characters personally, so I keep coming back for more.
This is truly one mangaka that I respect and look up to.