Can someone tell me what's so great about this game? I'm curious about the labels it has, but often they're just there to get attention.
How different are normal and hard difficulties?
This game is great for many reasons.
The gameplay is really good. It's turn based with an emphasis on status effect and skills. Basically your party will be afflicted by different status (I don't remember the exact number but it's AT LEAST 100) and you have many ways to deal with it (items or skills). You can easily be trapped by a loop of status if you don't know how to manage them.
You have also a large party (8 members) with different class and skills. More importantly, some status are a class on their own. It adds great variety to the gameplay and let you experience freely new party builds.
It's an open world. It's best to play the game without any guide at first and just enjoy discovering new content. But I have to admit that it's a bit confusing at first because the game doesn't give you lots of clues as to where you are supposed to go.
You have lots of content... really. You have plenty of boss, enemies, skills, status, bad endings etc. Also, keep in mind that it's definitely a "fetish" game (with a great emphasis on mind control). You have nearly no sex scene in the entire game. If that's not your cup of tea, you will obviously not enjoy the game at its fullest. The tags are correct.
About the difficulty, I would advise playing the game in normal mode just to get an idea of how the game is supposed to be played and switch to hard mode. Because when you know what you are doing, normal mode can be extremely easy because it allows you to use items without using a turn. Meaning you can cure the status of all your party members without any drawback if you have farmed the good items. In hard mode, you use a turn with every item you use, making it more fair and balanced. Hard mode isn't really that hard to begin with... but you will definitely struggle with some of the hardest boss.