Marmalade boy is, in a word, highly addictive. I watched just the first episode out of curiosity and ended up getting hooked into the story. The anime revolves mostly around Miki and Yuu's relationship, while touching on the love affairs of the supporting cast sporadically. The animation is decent for when the anime was made and the story and seiyuu are all very good. So at 76 episodes, watching Marmalade Boy is quite a time committment, but I think that you'll find that its worth it. Just so long as you don't mind soap-opera esque anime.