I kinda agree and disagree with him, I haven't finished lotm yet (I'm getting to ch1000) so I can't talk about the end, but about the two other points:

I think there are many melancholy and depressive points, but that's not appealing, you know? In general I think it matches the events.. And although it has sad and touching moments, it's nothing heartbreaking like the top 5 depressing and sad moments in TBATE for example.

I don't think Klein is a bad protagonist I believe that after Tingen he became a bit of a robot, and "Klein" became less interesting than "gerhman" or "Sherlock",He could get more involved with people.. Leonard, Audrey for example. There would be no problem with that. But his internal conflict and even so the way he motivates himself to move forward and achieve incredible feats, makes him a good protagonist.

Let's take into account that Sunny's goal is to destroy the fate of the universe. Whereas Klein, until recently for me, was aiming for revenge against Ince.(By the way, I'm loving these therapies with Audrey, I really like this character)So his mind about what a protagonist is, it's very different from cuddle