I feel like this drama is getting a lot of negative reviews so I believe I should talk about the postitive sides of 'Abyss' so hopefully new viewers are not scared to watch this drama.
Because trust me you not going to regret it!

Okay let me start with the most important thing. Plot/Writing. Which seems like a lot of people complain about. Now I'm not saying it was 10/10 however I was not bored for even one second or had any problems with how the story was layed out. We start off the whole drama with a lot of questions which I personally liked as it made it much more interesting. The action and the misery parts were truly amazing. It is a rom-com kdrama so I wasn't really expecting much of a twists and exitment but I gotta say that I've never seen such a well balanced kdrama. We got the right amount of romance, comedy, action and fantasy. Masterpiece.

Acting:
I gotta say that this was the first time watching a kdrama with An Hyo Seop and Park Bo Young ( because yes I did not watch Strong Girl Bong soon) and Oh my God. I am a fan. Totally. Without a doubt. I loved her acting as I feel like she was able to deliver emotion in a really professional way. She was truly impressing. As for Hyo Seop I kinda felt like he was a pretty face rookie actor and in the beginning I thought that would ruin his character however I felt like it suited his cute, clusmy and a little bit dumb character. A lot of people criticized Cha Min's character and I might have to agree with that a little bit as I think they could've give more to Cha Min. More charisma maybe more seriousness however I think it wasn't a big problem as his cute silliness suited the drama

Music:
I have nothing much to say about this. It was just truly amazing and I am usually really picky with ost as I get bored of listening to the same songs through 16 episode.

Ending:
Another element of the drama that I read a lot of hate comments about. And I seriously thought for a good 10 minutes that I'm gonna hate the ending. But obviously I didn't. To be honest it wasn't anything special we seen it before but sometimes extravaganza endings can ruin a drama. I'm gonna be honest this was the ending I needed. Sweet and chill. And nice refreshing ending after all the excitement.

Overall:
I seriously don't get why this drama is getting a lot of hate. If you are unsure of watching it, Trust me! It's a worth watch. Perfect plotwist. And it is just so entertaining!!!