I enjoyed how in the beginning it was light, silly, and just over the top funny. I always found myself cracking up at Zero Nine because he was like a puppy and kid rolled up into the body of a twenty-something year old man. The actor did an amazing job playing Zero Nine; even towards the middle where he is developing human emotions/understanding human emotions, you can still tell that he is a robot. I loved this because even though his character turned more human compared to the cute boyfriend robot from the beginning, the actor and director kept Zero Nine's initial robot quirks there. It was the attention to detail with his character that made this drama for me.
On the other hand, you have the other characters. I did love the romance between these two mains, and the ending made me ugly cry, but something just didn't sit well. I 100% felt the love that Zero Nine had for DaDa. It was DaDa I didn't quite understand. One day she just pulled a 180 and loved him with 100% of her heart, which is way more than we saw with the flashbacks of her and Ma Wang Joon. Maybe it is just me, but I don't believe the whole 180 turn. I don't buy it in real life and I don't buy it in dramas.
Then we have Ma Wang Joon. I do think he was a terrible boyfriend in the beginning and yes, she needed to dump him. I think there were two main things I disliked - 1) how he knew he was distancing himself from her for years and didn't care enough for her to treat her better and 2) how he thought their relationship was solely him making the decisions when he should have been communicating with her. After they broke up, I think it was just pure jealousy that she had met someone the complete opposite of him. I truly believe that their relationship was over a long time ago, and he only went after her to prove something to himself. And that is another thing I wasn't convinced with Zero Nine and DaDa's relationship - Zero Nine was the exact opposite of what Ma Wang Joon, all the things she wanted from Ma Wang Joon, was what Zero Nine thrived in. It makes me question DaDa. I read a lot of reviews before writing this one about Ma Wang Joon , and a lot of people pointed him the true villain in this drama, but I'd have to disagree. Yes, I thought he was a crappy boyfriend and person at times, but I also saw Ma Wang Joon's love for DaDa. Yes, I HATED when he blew up on both mains and basically dug himself deeper, but there were other times when he acted as a big brother, knowing that he saw how much he had hurt DaDa in the past and he doesn't want anyone else to make her feel that way again. He went about it in terrible ways, but the intention was there. I don't think I could hate him at the end of everything. He definitely needs to do some growing up.
The one person I disliked would have to be Diana. I loved how she was just this heiress who hates people and decides to make everyone's life miserable for no reason except for her own pleasure, but that's all she was. I thought she was going to have some kind of consequence or this huge redemption, but no. She literally was destroying robot after robot and stealing company property, and all she got out of it was she was put on the banned list. Like she has done so much that she could be sued for millions or in jail, but no. Also, she basically messed with Zero Nine and DaDa's relationship, especially towards the end which I will not say, and she did nothing to fix it. She apologized and then went away. She basically had enough money to spare to help out the situation, but she literally just left. They made you think that she was going to have this huge impact at the end and save the day - nope.

Overall, I feel like some characters lacked while others shined in this regardless if there were good or bad people. If you want to watch a drama (that dragged in the middle) that will make you laugh at Zero Nine's adorableness in the beginning, and then ugly cry in the last 5 episodes, this is the drama to watch.
I stand by my rating of 9/10 - I loved Zero Nine throughout. He was the perfect boyfriend. I loved how cheeky and cute he was in the beginning, thinking that puppy love was love. I also loved as he started to understand others and what true love was, he turned from an adorable puppy who was ok with a one-sided love to this sensual and emotional person who also wanted to be loved. I feel like he was the one who struggled the most emotionally in this drama which is wild cause he is the robot. If you are iffy about this drama, I think Zero Nine's cute puppy attitude in the beginning and then all the emotional scenes in the last few episodes are 100% worth the watch. You will have to go through all the filler BS in the middle, but it is worth it to ugly cry at the end. Wild that a robot that learned what love was from a human was able to understand what love was, better than anyone in this damn drama. Understood what sacrifices you had to make and were willing to make for the person you love.