Having just finished twenty one twenty five this exactly what I needed. There's nothing particularly original about the premise but the execution is spot on. As a romantic comedy it is light, breezy and very watchable.

The good
An easy, feel-good show after a busy week. Standout for me is the humour which only gets better as the episodes go on. Plenty of laugh out loud moments, particularly from the supporting cast. The dynamite drink scene and archaeopteryx are comedy gold.
The SFL and SML have a romance which is just as good, if not better than the two leads. In fact, all the cast clearly have good off-screen chemistry. Waiting for a K-drama with Seol In-ah and Kim Min-kyu as leads now!
Ha-ri is so likeable because she is determined and pragmatic. Her and Young-seo are the ultimate chaotic duo.
While I found Hyo-seop as Tae-mu a bit wooden at times, he succeeds in being the lovable dork who takes himself too seriously.
The Grandpa spends a lot of time huffing and scheming but I'm all for it.

The bad
Literally every K-drama trope. Not gonna win any awards but that's not why we're all watching it.
The first few episodes didn't exactly wow me but it's almost like the writers listened and cranked up the humour. At first I thought 12 episodes would be the right length but the ending did feel rushed. Personally not a fan of the long distance/time skips when they are shoved into one episode. Would have been nice to see more of them as a fully fledged couple and Grandpa giving them his blessing.