First, you need to know that anything over 20 episodes is likely to wear on you before you finish it. The criteria for a long drama like this are different than something that builds and ends in 16 episodes. Less drama, more time for characters to develop - and to be stupid. You also won't get A-list stars, either, so if one of the principles is trying to become a pro singer, he's likely to be pretty mediocre. All that said, there's something nice to have an extended family to visit with every week for a while.
I like an occasional long drama. This one is pretty good, although like most of them, it tries to wrap up too much stuff in the last episode. Each of the sisters' story lines deserved an episode to itself, and at least one romance was left totally hanging (poor Aunt and the singer's father!) when they deserved something better. So there were disappointments. But if you like long format dramas, this one is pretty decent, and far better than most.