After a brief flashback to the first use of the resurrection flower against the invading Japanese, S2 picks right back up with the zombies out in daylight, and a fantastic retreating battle, and heroic sacrifices winnowing the cast a bit.
There's more straightforward conflict this season, since we know who the villains are (anyone named Cho). A little of what they'd previously done fills in backstory, and desperate measures against the Japanese make sense, but not so much why they're still doing it; ambition, sure, but hitching yourself to the Queen's clan or using the plague as a weapon are not things sane people do.
A cop with an impressive feather hat tries to investigate the Queen, and gets further than I'd expect from feudal investigators, but politics makes that entire subplot pointless. She isn't especially cunning, her plots and tricks are very blunt and obvious, but nobody can call her on it, and her impossibly loyal guards and court ladies go along with it.
The Crown Prince does more swordfighting this season, though mostly it's hacking up zombies instead of duels. The "Tiger Hunter" peasant with a gun amuses me, and he finally gets one backstory flashback, but he's low on dialogue.
Nurse Seo-Bi in any other era would be a boss, with the most valuable medical/murder tool ever and the cure for the zombie plague, but in feudal Korea she's just pushed around as a pawn, and treats entirely the wrong person. Half the plot could be avoided if she just told the Crown Prince what she knows earlier, and doesn't help the villains.
By E3 & E4, I'm really missing the zombies; there's too much Human backstabbing and just chasing around the countryside which is zombie-free except at the surrounded fortress. And some of the death scenes last a very long time, many minutes of weeping and flashbacks.
Finally by E5, we get some zombie action again, but it's taken forever. Zombies vs guy in toilet is always a great set piece. The "camera following unseen action behind a wall" scenes get annoying quick; I prefer to see the combats.
"People aren't screaming. The screams have stopped."
"What's going on?"
The plan in E6 relies on zombies not being able to climb, which eventually they do, an ice lake breaking in a way that it doesn't (ice is bouyant, so breaking it in one place doesn't shatter the entire lake).
The "7 years later" setup for the next season is a little heavy on tell-not-showing, but we have a new villain teaser at least.
I did get bored mid-season. Zombies, ever since Night of the Living Dead, have existed to put pressure on people, and keep a plot advancing fast. Without the zombies, you just have people whining at each other, making too-elaborate plots, and they don't even have to stay in the house/castle. With zombies, you get desperation and quick, bad decisions in enclosed spaces.