The closing cutscene and choice was well done, as were the first two phases of the final boss.
The third though, it just felt like the game wasn't playing by its own rules; when you call a difficulty setting "casual" and the whole game up to that point is manageable for a player like myself, suddenly throwing a super hard boss into the mix just doesn't feel fair or respectful of the player.
It's not a dealbreaker, just something I wish the game had done a better job of considering everything else about it is so good.
I agree, the final boss is so difficult compared to the rest of the game, it really feels out of place. Congrats for still beating the game!
On a side note, the same issue is present in Daemon X Machina. The final boss is super hard! When I got along the whole game pretty fine but then the final boss kicked my butt over and over, I asked myself if I played it wrong the entire time. At least he had an amazing boss theme, so that's something. Funnily both games released pretty close to each other.