Cons: The Ruijerd storyline. Zzzzzzzz.
Bad stuff first then. The Ruijerd storyline is suddenly and abruptly completely boring as shit. I don't care how you want to count Mushoku Tensei as the "godfather of isekai" the whole, 'You mustn't kill! Even the bad guys!?' plot thread is so old and trite at this point it's not even interesting.
Mushoku Tensei started in 2012/2014, and this trope was old in anime THEN. It was old in 1992 for Terminator 2. It was old in
Dragon Ball. I'm honestly not even interested in seeing what (if anything), the series will attempt to do as a different spin. I feel like I've seen every possible iteration of the trope already, and it isn't even an interesting or compelling one to begin with.