Note: this is an incomplete review as the series is still running.
Admittedly I almost checked out of this show after the first couple of episodes. Between the flashbacks and some painfully slow character development, you'd be forgiven if you lost interest early on. But if you manage to get past some of the more forgettable background-setting you'll be rewarded with a much better story that lies beneath a very superficial beginning.
I think a lot of K-drama series that originate with Netflix are hurt by the typical 12-16 episode series order. The first few episodes of "Welcome to Samdal-ri" are focused on the events that bring Sam-dal back to her home on Jeju. It's a catalyst that gets the story into its primary setting, but it's not the main focus of the overall arc. The relationships between Sam-dal, Yong-pil, and her family and friends is where the real heart of the story is. A half an episode focused on the abuse of power scandal would have been enough to propel the story where it needed to be.
Once you get to the root of the story, though, "Welcome to Samdal-ri" begins to shine. The multi-layered relationships are very smartly woven together and facets revealed at a good pace. The comedy provided by the haenyeos and the sisters (particularly the relationship between the older sister and her ex-husband) are evenly balanced with the tragedy that underlies the main story arc. By the end of "The story of the two Mi-jas", the series is hitting all the right emotional notes.
Upcoming episodes will return us to the abuse of power story, but I hope it doesn't linger too long there. The real heart of "Welcome to Samdal-ri" is, like all good K-dramas, in the relationships of its characters. Revenge stories have their place, but this series is so much bigger than a revenge story.