WARNING! SPOILERS ARE CONTAINED. PLEASE IF YOU DON'T LIKE SPOILERS THEN DO NOT READ THIS! THANK YOU!

I've watched the previous seasons and found similarities and differences as well.

Of course, the soundtracks are on point as well as the acting. KLANG's husky voice and Kang Seung Yoon"s calming voice makes this drama unforgettable.

Lee Ha Na is amazing as always and Song Seung Heon gives a different vibe. The chemistry between them won't disappoint you.
I also think that Son Eun Seo, Kang Seung Yoon, Lee Kyu Hyung, Baek Sung Hyun, Kim Joong Ki, Song Boo Geon, and Han James portraited their characters well making it to be worth watching it. To be honest I was curious about Bake Sung Hyun...
He didn't disappoint me.

Basically, the two main characters' partnership starts similarly to the previous 3 seasons. This time, Director Kang's partner is different from Team Leader Do and Moo Jin Hyeok. Based on the storyline (and seems like the next and maybe last season ) I think it was important to make a different character like Detective Cho.
This is what made me like this season.

There is one more thing I liked about this drama.
As the title said: meaning of having a family. As you will see this drama shows the different approaches to being part of a family: what makes you being a family member and why this is a beautiful thing. Also, this drama's purpose was to attract attention to a serious problem (which does not just exist in South Korea but in every country): domestic violance. I recommend watching all of 14 episodes to understand what I'm talking about.

Thank you for reading this. I also recommend you to watch all 14 episodes because a surprise is waiting for you.