I agree that the kana were pretty good. Everything after that was just incoherent and I'd rather sit down and read through Genki instead, memorise what I learned with a Anki deck and maybe even spend some money for a teacher in iTalki. I've also had good success listening to Michel Thomas recordings while commuting. While none of this except most versions of Anki is free, neither is my time and learning a language especially Japanese is a massive time investment to begin with. I'm happy to throw money at the problem, especially if we talk $50 for a text book or $15-$20/hour with a native teacher.

Measuring Duolingo’s quality by kana learning is not a good idea. Kana are so simple you can learn them in a week using any method ever. What Duolingo fails at is the important part of learning Japanese (aside from kanji) - grammar and sentence structuring.

You’re much better off reading an actual textbook.

I personally don’t hate on Duolingo because it’s free but it tends to waste people’s times and gives them false impressions about language learning.