Things i liked:

The cast was absolutely flawless. They managed to express everything perfectly and that made this drama 100x better. I have huge admiration for Seo Kang Joon,playing two different characters is truly hard but he did it effortlessly.
The plot was interesting and unique. It wasn't a typical robot "turn into human/is actually a human" story and that surprised me. The drama was equal parts lovable, action packed,hilarious, and touching.
Also,the OST was one of my fav so far. I would definitely listen to it on my free time.

Things i disliked:

The last 2-3 episodes. Some plot scenes were dragged a little bit and the ending felt rushed and left me with a lot of questions. I feel like 15 minutes were missing. The writers could've explored more and present us a more detailed and extended ending.

Overall,it was a really enjoyable drama,it had a great balance of light and heavy moments, intriguing storyline and amazing acting. I would recommend watching this.