It's a pretty good story. It's not like a cheesy romantic one and contains a lot of comedy. However, it's one of those romances that you love but don't really want to accept.
The whole step-sister x step-brother thing is kind of crazy. Not to mention when your parents are all in love and stuff with your boyfriend's parents... It turns out all okay in the end (being a shoujo manga and all), but it's kind of hard to picture in real life. The parents are crazy people too, they practically act like teenagers.

If you're open minded to the concept "love conquers all" then i suggest you go for it!