I think one of the best things about this series is how gradual it shows self-improvement to be. Instead of shit like people changing for the better overnight, it meticulously dissects the reasons and mindsets that make bad habits hard to die, as well as all the small pitfalls on the way towards meaningful, lasting change. And instead of making it overly dramatic like some series where the key for everything to be set right is for the protagonist to overcome ONE mental block, which always happens in a climatic moment of realisation, in No Home characters (mainly Haejoon and Eunyung) have to build themselves up almost from scratch, and every little aspect of their original mindsets that gets in the way is addressed consistently. In the end, we have to compare them not to who they were 20 chapters ago, but 200 if we are to really feel how far they've come. And it also shows how no man is an island, how every supportive person is important, how nobody is truly "self-made".
Sometimes reading it feels like torture because as karmscharms above has remarked, at every twist and turn there seems to be danger of all the progress evaporating and our protagonists (mainly Eunyung at this point, though Haejoon isn't quite out of the woods yet) reverting to self-destructive behaviour. And the danger feels real, because we know each little step has to be accomplished successfully for them to be able to take the next one.
Truly a joy to read.