The writing and investigation work was subpar, Ranpo is insufferable, Atsushi's past isn't fully explored nor is his sudden proficiency with his ability explained. Dazai's suicidal tendencies were inconsequencial and his sudden serious behaviour was off putting. The fight between him and Kunikida was never actually resolved, what the hell? Some moments in the show were made to be melancholy and dramatic yet it's almost like the conflict is immediately forgotten. Plus, the show never really decides which side of the over-arching conflict it will focus on.
However Dazai was extremely likeable and Akutagawa was the best written character by far. The action made up for the janky story. It wouldn't make sense to give this season more than a 6 honestly. Still, go watch it, it's not shakespeare but it's bingeable.
