Art is decent. Story is "Okay".
We get a simplification of the MC and his GF's adventure in another world(with Time Dilation[They were gone years, but only about a year in their home world]), and coming back to their home world, and then having to deal with typical cliches from every school-based story ever written. Add "dungeon portals appear all over the world!" as has been done in at least four different SKorean comics and many Japanese series.
We're pretty much getting a Japanese story with SKorean comic style, both long-form style and art style.
I'm sure that as it progresses, it'll end up making more sense, but it's still early days yet... and it might end up being better than several of the SKorean series that can be real messes... scratch that, most series like this end up making little sense even in the end.
I'll give my interest in it a 6/10. It's not "bad" yet, but it's nowhere near "great" yet.