The story's first 2 eps were great but started going downhill from there.

First the entire premise of the disease. Think about it. The fact that a thin sheet of glass is holding off blood thirsty creatures both at the basement and the first floor. Glass that could be easily broken with a real impact (anything from as ramming car at the basement to a thrown chair at the first floor)

The writer tried to cover the hole with an excuse that the zombies did not do this when lucid because they wanted to avoid becoming complete monsters.

Match this against the guy who shows up multiple times at the basement trying to trick them into opening up. He is deliberately trying to enter but apparently if the door is opened for him instead of him smashing the glass, it doesn't count as becoming a monster? Huh?

Then we have the complete failure to account for those who would see the world burn along with them (aka infect everyone since you yourself is infected). These people would break the glass just to allow the disease to run rampant. This is despite the portrayal of many personalities in the block including "he who unmasked at the end and shall not be named" and the doctor of accidental comedy

Other than this massive mobius strip logic, we have the writer letting off the comedy doctor, who despite his first criminal act and being caught red handed in subsequent criminal acts, is constantly allowed to run free. Yes, the writer needs a catalyst to move the story but a *cop* who has handled criminals somehow has a "heart of gold" so much that the doctor is let off. Repeatedly. WTF

Then we have the inanity that is the toilet scene. If the female lead was not a SWAT team member (where split decisions must be made accurately) and is portrayed as a vengeful, consequences be damned woman, then that would be fine. But a SWAT team member knowing a bite is 100% infectious, having an unlocked toilet door that she herself could pass through and close behind her, decides on that.

We next have the consistent and deliberate failure to pass out relevant information. Just the last episode, the old man is told to not open the door for strangers, when a simple explanation of who he was referring to and why, would have made it simple. We can see this in prior episodes. Suddenly blood being used to identify infected is mentioned, despite the fact that the method could have having solved a lot of problems from earlier. Explanations of thirst being a symptom is also only mentioned after things explode.

The motivations of the doctor also ping pongs, from injecting xyz into the water to saying he wants xyz to protect himself. As the deus ex machina, he gets immunity and smarts as and when he needs it. Like the handphone recording, which he somehow knows its effect, to the knowledge of how the priest's sight would be blurry, to complete ability to predict the block rep's response after the supermarket raid.

Then we can see that someone told the writer to wrap it up ASAP because by a miracle, the Mr ABC has the components for cure! Oh wow, in the last episode, such amazing timing. This is despite having a whole country to find one and a failure to find a correct one (showing the probability as being minuscule and the other candidates give effects such as the one the colonel's boss experienced)

Overall the show is saved by its actors (minus the male lead). The doctor's actor despite given illogical motivations portray him well enough that he grabs the scenes he is in and amplified by the male lead letting him go again and again, he can get on the audience nerves which shows his acting is really up to par. The colonel also does really well here. He is the only one who foresaw the scenario and took actions to stop it. The colonel's boss was a just a bit part but the guy acted well enough to make people want to beat him up. The old policeman was actually pretty good in how useless he acted (qv that scene with the screaming handphone). The cleaner couple and the lawyer couple played their parts well enough. The female lead did ok, injecting a lot more energy into the scenes she's in but the male lead's expressions are just stoic, stoic smile, stoic wistfulness, more stoic.

Music and sound wise, there wasn't much to look at other than a few overly heavy handed and thus immersion breaking melancholic songs played at the points where "Be Sad Here" is tagged.