I watch a lot of Korean television series, although usually with more of a crime/corruption/conspiracy angle. However, my K-drama queue was a little lean and this did have strong reviews so I gave it a go. I'm glad I did. Exceeded expectations.
Great cast and cast chemistry. Solid production values including the sets for the Joseon era. Good writing both in terms of the broad plot and related subplots as well as the dialogue. Thanks to the visits to the Joseon era, viewers will be introduced to a couple of historical figures from the time. While time travel is the foundation of the show's premise, it doesn't trouble viewers with the paradoxical nature of time travel and its implications. More writers of time travel shows should also avoid it, few handle such matters well. To the extent the writers want to encourage more philosophical ponderings, it is more about the differences, and similarities, between Joseon-era and modern Korea.
Satisfying conclusion - be certain to watch to the very end: there is a brief coda after the final episode's credits which will give the viewer a last smile about the conclusion.
If you are looking for a Korean drama with a strong dose of humor, a modest amount of romance and an interesting story, I'd highly recommend it. If you're new to the world of K-dramas, it might be a good introduction.