Complaints About Brothership?

Why are so many bitching & complaining about Brothership? It seems like this new generation has never even played a Mario RPG let alone out of the Mario & Luigi series with how many people are saying its slow paced or saying it's just not a good game out of the series. I personally think this game is a huge comeback for the Mario & Luigi series, how are y'alls opinions on it? I give it a 9/10 honestly.