This is one of those fluffy, easy-watch dramas that are easy on the plot but amazing on the acting. The story is unbelievable, almost nonsensical, but the actors pull it off and so well that you can't help but admire their acting. Although, the overall concept is kinda crazy, the plot itself is very well written. The punches are great and well on time. The romance will not give you any intense satisfaction. Instead, the romance is sweet and innocent and fluffy. Some scenes are hilarious.

Coming to the cast. I am not particularly fond of Chae Soo Bin, but this drama definitely changed that. She was perfect both as the robot Ah Ji and the street smart Ji Ah. Yoo Seung Ho was ADORABLE! He was the best thing about the show! I've seen plenty of his works and I think by far, this is my favorite character portrayed by him. This character really suited him so much. The supporting cast was really good. Loved Ji Ah's friend and her brother as well as his family. They were all great. Sun Hye's little love triangle was awesome. lol.

The music was great. Perfect amount of chirp and serious.

I would definitely come back and watch it for the adorable character of Kim Min Kyu as well as certain hilarious scenes. Also, someone needs to invent those things Ji Ah made in the show, but sounds a little difficult from science's POV, lol.
Anyways, if you are in a mood for an easy-watch, this is definitely your show!