After watching the series and feeling awfully disappointed, this special episode was a breath of fresh air. Time-travel to the past version of oneself isn't a trope I like at all, I usually avoid it, but they managed to use it in a cute way that somewhat gave me relief from the bitterness I felt over the main series.
The plot itself isn't anything special, but it works for a single episode like this one. The characterization, the chemistry AND the acting felt way better in every aspect, so much that I wondered if the production team is the same or if they changed it for this one special episode. The music is the same as the rest of the series, so while it's not great, it feels like an actual sequel and not like its own thing.
It almost made me wish that the main series was about Li Gong and Ze Shou in high school.