Without touching too much on the things that the summary doesn't allude to, I will give my thoughts on My Perfect Stranger.
I cannot recommend this to anyone who is looking for a sci-fi drama. This drama is like 10% sci-fi and there are so many questions I have for it. I want to call them plot holes but they honestly aren't considering that characters in the story don't even wonder about them themselves. It's like the writers just assumed that since the characters don't care that we wouldn't either.
Although the leads DO form a subtle romantic relationship, you will find a sweeter romance with the support characters (FL's parents). The best part of this drama is the relationship you'll see between them and the FL's family as a whole. It was beautiful and touching and I actually teared up multiple times. I was not expecting a murder mystery drama to be so warm. This aspect honestly makes the whole drama worth watching
The mystery and investigation part of this drama was also very interesting. You'd never guess who the killer was until it was plainly laid out. That was a good and bad thing. As the investigation deepened and the case was solved, everything made sense, but it sometimes just felt like the writers made certain things happen just to be sure that they could outsmart the viewer.
Although I enjoyed this drama while it was airing, in retrospect, I would've enjoyed it more if the characters had a bit more passion. It seems like they never fully felt any particular emotion.
Overall, a good drama. 8.5/10