I meant to post as soon as I beat the game, but I was too exhausted and had to sleep for a few hours.
WOW, what a joyride! 10/10 in my mind, easily. I ended up playing it all in one sitting, actually streaming the whole game. Was an absolute blast, with crazy bosses and an insane amount of combat. Never got tired of the main type of combat throughout. Some of those bosses are absolutely bonkers. And bosses were incredibly frequent, as were challenge rooms and other fun distractions. Heck, I'm about to start streaming it again, was just too much fun and all I want to do is grab the gamepad again and play all weekend.
So, in case anyone has experience with these kinds of games, I may have a suggestion if you haven't started yet. You should probably play this game on the Hard difficulty (3rd climax) from the onset. I did it on the Normal equivalent, and it was way too much of a cakewalk. Never had to use an item, never died. Personally, the viewers said I rushed through the game, even though I felt like I was going at an actually pretty mellow pace...but whatever the case, the game was just a few minutes over 8 hours for me to complete.
Argh! So good, so so good! I have nothing really negative to say except I really hate it in games when the AI is constantly telling you to "hurry up!" but the game itself is encouraging you to look around and explore...got old really quick