Meh. Started with a great premise, only to faceplant the ending like typical K-drama. The start was good, it build up the tension nicely, albeit slowly. The time slip plot was pretty interesting with overarching plot and subplot romances.
By the end, the main couple was concluded half-heartedly, none of the other characters or romance found their catharsis or conclusion, the conflict and trouble that has been built up from the beginning was solved in the weirdest non-twist and by the end the problem was apparently the time slip mechanism itself and by erasing it and undoing all the effect of the time slip is the solution itself. That means the whole thing was pointless and had it not existed in the first place, none of the conflict would have happened in the first place. All the time slip did was to give the deuteragonist heroine a fuzzy warm feeling and give the hero an inclination that there's apparently love out there that he found, forgot and will meet again... eventually. And that's it.
By the end all I could think of the series is, "It's a cheap knockoff of Kimi no Na wa / Your Name sprinkled with Indy doesn't matter theory."