I apologise in advance to people, as this is a rant.
For starters, this is a really good manga because, even though it follows many clichés found in shoujo manga, this makes it wonderful as it doesn't rush the story, and is the natural progression of love between a hater of men and... Usui, for lack of a better word. The fact that Misaki doesn't suddenly turn around and says "I love you!" and they live happily ever after, adds to the realism, as it takes many trials and efforts for Usui to squeeze into Misaki's heart. Also, the fact that after becoming a couple, he hatred for men doesn't diminish, but over time as she makes new friends, and even how she still acts like Misaki around Usui, even when dating.
Secondly, Misaki is tsundere. Meaning she is prone to dramatic changes which makes her ever so loveable, people who say she becomes a blushing idiot. You're the idiot, as that is the essence of tsundere, otherwise it would be just tsun, an angry, violent, unloveable female dog that would be boring for a main character. She becomes more tsundere in later chapters, but less tsun and more dere as Usui slowly becomes important to her.
Thirdly, Usui has been, from the very start, and always will be, a pervert. It's what makes Usui, Usui. It isn't forced, but a natural feature he has. For those who say it's forced or unnatural, are idiots too. If he wasn't perverted, it wouldn't make him Misaki's most incompatible guy, and therefore destroy a somewhat mismatched couple element. Also, he wouldn't have been able to break down Misaki's defences like he did.
Fourthly, Misaki doesn't change when she becomes a couple with Usui. Yes she may become more dere than tsun like she was with him, but that's the point. She changes, not to an absolute different person, but to a more open person to him, like he cracked her shell. A relationship is good if it changes people in that way.
Sorry for the rant. This is a worthwhile manga with a realistic love story, even if people have personal preferences which deny this. For me, however, it was truly the best shoujo manga I've ever read.