Maybe not bad, but not my tastes. Personally I found it too heavy on the comedy, it might even be considered slapstick. But if you like a lot of comedy and only a splash of romance then maybe you will like this, if you can overlook the next issue.

People trying to reduce this to an age gap show are missing a fundamental issue. The gap isn't the issue, the problem is the grooming that is heavily emphasized and treated as romantic. She was literally his teacher and idolized by him. They emphasize how much he has put her on a pedestal because he was going through such a rough time in school at the time and was super vulnerable. This is not a background part of the plot, it is a core part of his character that dominates multiple episodes. This is actually text book grooming, so to give it the kdrama sparkle of romance is really uncomfortable.

Weirdly they also just show her desperately clinging to men, at least from what I could see, she just clings to whoever is in front of her, which made it hard to feel like the character had any dignity or the prospective romance had any value, since she's just willing to settle for anything.

Beyond those issues show was decent, the characters and acting are good, and the broader plot about the historical preservation people is really interesting.

Though I found it weird that his character is supposed to be a devoted historical reenactor type, but has a modern haircut? I am by no means an expert, and even I expected him to have his hair tied up on the top of his head, especially wearing that hat, it was jarring to have short hair under it.