Id have to say this music, from atleast a Classical standpoint is excellent and I truly believes captures the nature of the show and its many 'rich, elegant' characters.
The songs are filled with emotion and really help you connect with the show while watching it. Infact, many of them are quite beautiful and sad.
I give it a perfect 10, a seriously excellent soundtrack that can be listened to on its own, but definatley should be experienced with the beautiful imagery in Ouran High School Host Club.