I'm about 50 hrs in, don't know how much I have left, just finished the mines with Yuffie. The combat and the music are phenomenal, there are also problems.
I think it suffers from what every open world game suffers, fatigue, pacing problems, checklists. It has this formula of story path focused area followed by open world followed by story path and so on, this is the structure of open world games, don't really know how you can change it.
What irks me a bit is that sometimes little unnecessary actions break the flow, like check this - cutscene - walk there a short distance/push button/lever - cutscene.
I get the complaints, but I also enjoy most of it, because of the combat and the music, also if I like a game because of these reasons, I tend to do everything, no matter how bad it is, I'm retarded that way -- it happened to me as well with Nier Automata, the combat and music combo.
I would call it a flawed gem, with all its stuff I don't like, it's truly something special.