I personally really like this series. Though I'm relatively new to manga (and the shoujo genre, which is my favorite), it may be too cliche for some, but I still think the characters have depth, even though they may not have "evolved" yet. (It took several volumes before the characters truly started to evolve in Ouran, for example.) I can easily envision situations and how these characters would react, which to me is a sign of good character development (if you can think like the character). Perhaps it was easier for me to like it because I didn't start it until there were 4 volumes released and I could sit and read them all at once.
I like the artwork. Quite often you see the heroine with a particular standard 'look' with occasional changes for a specific situation, but Sachie has many different looks, hair and clothes, which I've enjoyed. Rakuto and Azuma are always good eye-candy.
As for the story, it is a bit more episodic than other series I've read (meaning stories don't often bridge many chapters). I'm not sure if that's a hinderance to some readers or not.
I like the fact that it's not particularly a school-based storyline; as much happens outside of school as happens in it. It's about Sachie learning what it really means to be part of a Yakuza family, which isn't limited to school.
I can easily feel how torn Rakuto is between his feelings and his fears of ending up like Jin; how confused Sachie is with Rakuto's radically changing personality; and how miffed Azuma is being caught in the middle of them. And then there's Asagi Raizo-san, who is as shrewd and sly as they come.
Even if the whole storyline is fairly predictable in its eventual outcome, I still really look forward to reading more books/scans of this series.