This is one of those family drama that actually focus on the "family" instead of the "romance".
Despite having a few couples, each one with their respective sup-plot, the romance shown is very little.
Lee Sang Woo & Han Ji Hye are set as the main couple, but they weren't the real OTP, they got the same screen-time as others, if I have to be honest their sub-plot wasn't even that interesting and I end up loving more other characters.

The main topic of the drama is the relationship between parents, children and siblings. An old man met his first love and the two decide to start a relationship. While the eldery couple is facing its own love/hate relationship, their respective children are having an hard time to get along with the idea about becoming a "new large family".

In particular the woman's son is strongly against this relationship and while he try hard to break them up, he also clashes and established an ill-fated relationship with his future step-brother. This two characters will delivery one of the best enemis/bromance ever seen in a drama.
In the meanwhile all the other siblings, all daughters, are dealing with their own problems, each sub-plot will add drama to the already complicated dynamic and the two eldery will end up suffering a lot while dating and trying to cope with their children needs.

Each sub-plot is filled with typical family drama clichés, but despite the classic elements, the writer was able to write a balanced plot, giving to all the characters enough screen-time to properly develop each story, some more interesting than other depending on you personal taste. Despite some dramatic moments the story is full comedy, in particular the trio twins VS step-brother will make you cry from laughing several times.

Even if everyone have his own story, from the beginning it is obvious that Kim Kwon's role is the most important one, his behavior is what create the major conflict for the eldery couple and the sibling, it is also the character more involved in the main plot-line and different sub-plot. It's the glue that holds the story of the two families together.
It is one of those character that you cheer for cause he truly deserve a "character" development and an happy ending.
Although this character will have a strong change, unfortunately the writer failed to provide him with the romance he deserved, forcing a love-line that we all know it will not work out, cause from ep. 1 it's clear that the girl's heart is already taken.

During the last 20 episodes the writer decided to do some "lazy" writing and came out with a few draggy and ripetitive sub-plot. Some of the characters face the exact same issues already seen in the first part of the drama, with the addition of two hated clichés related to birth secrets and memory problems.

Overall it was easy to overcome those "eyes roll" moments and enjoy the rest of the story.
I hope you will enjoy Kim Kwon's role and the twins as much as I did.