Like:
+ the acting is quite okay
+ i am not sure what to think about the chemistry. i guess..its there? but the main problem is the story. i'll get to this point later
+ nice ost.
+ visuals

Room for improvement:
- i didn't like the female character. she was absolutely annoying imho. i just have a problem with people like her, lmao. she's way too intrusive.
- the story lacks excitement. it was just..a bit boring. i would've wished, that his insomnia gets more room in the story. or more depth. it felt shallow. at the end there are some open questions, which i didnt got any conclusion for. nothing major, but little things i would've like to know.
- the whole plot felt a little bit like a mess and all over the place. as if someone would start several things, but doesn't tell them till the end. i guess that's also the reason why i don't feel much chemistry. because the story doesn't feel connected. so.. yeah, well.

it's okay to watch, but it's definitely not a must-watch. and that makes me actually a bit sad, because i was really excited for this drama. ^^'