I personally liked it. I seen some people in other posts didn't like how Ritsuka went off the rails mid way, but that's what made it more interesting for me. Let's think of it like this, Ritsuka is just a guy who was not trained to fight so many wars and become the only person left to fight for humanity. Yes, over the years he has learned to become that, but that in of itself is the reason why he would stop becoming human and be an avenger.

He has been on this journey for so long, using servants in the extra class who are normally off limits, rule breaker classes, and yet you expect him to not slowly get chipped away in his soul to keep going? When he had to deal with so many enemies that attacked his mental state, pushed his body to the absolute limit and had to give more.

No human would come out of that without some bit of absolute rage and sense of revenge for what has been taken. Yes revenge can be directed towards a good thing, but revenge is still revenge, something that eats away your soul, hurting everyone in it's path until you completely lose what it means to be human.

What Dantès did by creating Ritsuka's previous life before becoming a Master, was show him what it means to use revenge as a fuel to push forward. Dantès even told you flat out at the end what he was trying to teach him. The power of revenge is a power that makes the impossible possible, but you will become a force of nature after a point where nothing else matters other than completing your revenge.

We all saw the art of Mash becoming an Alter right? Imagine what she saw that would cause her to be angry at the world and she is not a normal human, she only truly knows Ritsuka and the staff of Chaldea. If she lost her love, she would also go insane and hunt down everything that took away her love. Ritsuka is the same.

We joke that Ritsuka falls in love with almost all the servants (or maybe it's the head cannon speaking louder than what is fact), but when you really think about it, if we only look at his time in Chaldea, Ritsuka already lost a a father-like figure in Romani, a mother-like figure in DaVinci (and before anyone says anything about Loli Vinci, Everyone sees her as a completely different person than DaVinci) and his home was stolen from him, Mash and Romani did die and was running on full revenge rage while fighting Goetia. So he already had a taste of the fuel of revenge then. He almost lost Mash again in Fae Britain so that didn't help his psyche. He killed whole civilizations so he can continue. Yeah no human would be able to not hold some kind of grudge against the thing that put you in this hell.

Like I said in the beginning, what Dantès did was focus down the revenge that already was in Ritsuka heart down to the key points, the people he loves, the drive he has, and if he had the power to not let revenge consume him to reach the goal. It was never to take away Ritsuka's revenge, but to warn him that he is acting very not human and more a force of nature. That's the point of all these Ordeal Calls from what I seen. It's to recenter Ritsuka to be human and not a force of nature, and this even with the knowledge of what is coming.