Yeah, as other people have warned, this game's grindy as hell. Itoi got disinterested towards the end and the game gets ridiculous. It's also one of those early NES JRPGs that doesn't give you a lot of direction, and the middle part of the game doesn't even have a lot of people to talk to, just exploration. It doesn't have the level of detail or streamlined gameplay mechanics of the other two Mother games either.
Still, it's got a few of the things that make the games distinctive. Most notably, it's got the huge world with no overworld. It's got the setting. It's got the focus on emotional moments and varied situations.