I truly adore this series. Started reading it when it was still ongoing, waiting for each chapter to be released, up to it's conclusion. It's a simple premise; a girl has to crossdress as a guy to pay off a debt to a host club and while it starts as a comedy with any hints of romance played for laughs, it later on delves more into romance as feelings become clear and hearts become known. So comedy -> romance, but it does both quite well and the comedy isn't completely absent when the romance kicks in.
First and foremost, Haruhi is the straight man in a world of boke, thanks to Tamaki and the Hitachiin twins. Haruhi, constantly straightforward, blunt and ruthless in words as she's cute, she's one of the sane ones of the group and even becomes accustomed to the antics of the Host Club instead of remaining in a constant state of unchange and a cycle of non-development. Think of it as a circle, but she breaks free from it. Development, essentially. The same goes for Tamaki and his... stupidity. Truly, he is, quite frankly, stupid. Everybody knows it but he's a lovable idiot. There's something endearing about his rampant stupidity that makes you side with him.
I could go on and on, but the characters are truly brilliant. They start off as the host club/shoujo male types; stoic, lolita, narcissist etc but they get developed into characters instead of just labels of types. Even secondaries get development outside of interactions with the host club.
And when the romance kicks in, so does the drama. It gets more serious than the first half by far and turns to the development of the lovable King and on those in the heart of the romance. But with great romance comes drama, eh? It goes past mere drama in just those in the romantic entanglement and into the Host Club itself as a whole.
The art starts off quite good and develops over time. The change is gradual but from the beginnings of Haruhi's adventures in the club to the final chapters, there's an improvment without moving too far from what she began with. It retains the flavour of old while improving to make it a version 2.0 while keeping some of the visual quirks from early on. Keeping the good, improving the rest.
Praise, praise and more praise. Once again, I loved it. For the comedy at the beginning and the character interactions; the latter half's romance and drama, the character development and antics the host club conduct throughout, it harbored a special place in my heart through it's run and still does when it ended long ago. Come for the comedy, stay for the romance.