Overall plot's been done before, but the execution and character development are decent and the humor is on point. Add the fact that some of the scenes are well done despite the renders having been made on aging software (Honey Select 1) and it being the dev's first VN, and you can see why some people value it highly compared to somewhat more polished VN's in this site (i.e. CoBD, Depraved Awakening). Bonus points also for the dev's work ethic and completing the game without making it overstay its welcome.
Also, not every story needs to have a tragic or bittersweet or downright depressing outcome. Too often have stories in this day and age just make things so bleak and serious that when we do get cheery endings or no-drama resolutions like OIAL's canon ending it feels too fantastical somehow...which shouldn't be the case. And while I agree that OIAL could've been better if the story had more struggles and certain events weren't resolved quickly, having the entire journey be disregarded for some Mr. Robot-tier twist ending is just absolutely bad storytelling, especially since there were no hints or foreshadowing that would indicate that the story could possibly go for that kind of direction.