Game simply has too much going on at once, and there are moments where luck just decides you lose. The addition of the music box makes it so you will be spending your entire time looking at 2 screens, which while was also true for FNaF 1 at its hardest, its true here for the entire game. The mechanics of Foxy aren't explained well enough for how absolutely crucial they are to the game, which can really hamper anyone not already familiar with the game. Character designs are good at least.
I'd say play this if you want to gain a greater understanding of the series, but nothing more than that.