General spoilers only at bottom of review.
A gentle slice-of-life that feels recognizable in many aspects and is ultimately heartening. I ended the series with a long-lasting smile on my face, and sparks of warmth in my chest. The romance is sweet and endearing with physical attraction and gentle yet realistic kisses.

While the plot and character dynamics are not new, I thought they were handled very well. There's some drama yet things aren't forcefully over-dramatized. I've seen other people, or been myself, in situations or relationships like those here. At work, at home, with old crushes, new crushes, exes, co-workers, friends, etc. There are tie-ins to memories and regrets. There's living worn down and finding/making priorities. Characters work to untangle their own emotions and navigate awkward situations others put them in.

And the acting supports that feeling of familiar realism. The two leads are especially good and there is a gentle but persistently strong magnetism between them. I would readily watch them act together again. As actors, there is sincerity in their lines and behind their eyes. The rest of the actors were good with their roles too. No weak link stood out.

The balance of emotional moments was very well done. There was a little bit of everything, which is part of why it felt realistic. But there was an overall trend of increasing warmth and positivity that led to a very satisfied feeling by the end.

The dialogue flows and there are some poetically-worded lines. There were also a couple moments/lines of humor that had me chuckling.

I expect I will rewatch this multiple times, alone and with others.

GENERAL SPOILERS below.
I really appreciated how a few things were written a bit differently than often seen.

1) The past connection and the way it was remembered differently by Yoon Soon and Doo Hoon reminded me of the way stories were told at my college reunion. It felt plausible and very believable.

2) The way the coworkers reacted to finding out that Yoon Soo was Do Hoon's neighbor and romantic interest. It was refreshing, and how some people I know would likely react (and how I wish others would).

3) Yoon Soon's flight plans don't lead to the typical "airport scene". Booking plane tickets may seem like a big action, but it’s the equivalent of going on a road trip to Jeju Island for a breather before the real opening of his restaurant. There were multiple issues with his soft opening and things he needs to plan yet, so he needs to think through those. And things between him and Doo Hoon are at an awkward point, so wanting some physical space to "cool his head" makes sense because they are such close neighbors (they share a wall).