It's good. But it does not reward exploration or backtrack. I like to backtrack a lot, so half of my play-trough has been running in circles to get... nothing. 6 hours in and I feel like I'm not even in the half of the game, but not in a positive way
It's a game that rewards people who likes straightforward paths. I will need to change my strategy and just follow the level design without thinking much in what I left behind
About difficult, it's good and balanced, at least on normal mode, to have a fair challange. EMMI sessions are starting to get annoying though