I'm in the exact same boat? I'm French and I've been learning Portuguese for about a year now, including on Duolingo. I currently have a 203 day streak and I had a ~100 day streak before that. I've been using the "Portuguese for English speakers" tree because the French counterpart was so filled with typos in the basic lessons that I didn't trust it. I thought that the more popular English version might have been better reviewed. I mean if they can't even proofread the text of the "Basic 1" lesson the rest probably isn't better.

The streak is actually the only thing I really like about it, I want to keep it going because it shows me how long I've been working on it. For everything else I completely agree with you, Duolingo is borderline worthless for actually learning a language IMO. I can make a random list of complaints in no particular order:

- The spaced repetition aspect is ridiculously poorly calibrated, at least for me. Basic words decay way too fast which means that if I actually try to keep the skills "golden" (in the pre-crown era) I keep drilling the same basic skills again and again. Anki or Memrize manage that tremedously better. It's not even that complicated to implement correctly, I wonder why it's so crap. Maybe to keep you coming back and stretch the existing content? Now with the crown system they got rid of skill decay altogether, instead having you drill the same sentences an ungodly amount of time to reach a higher skill level. Also no matter how much I've drilled any lesson the majority of the exercises are asking you to translate foreign-to-native instead of the other way around, which would be more interesting as you improve.

- The actual "lessons" for each skills are so bare bones that they're basically useless. I think they know that since I don't think they're accessible at all in the android app. I know that grammar isn't sexy for most but if you want to learn a language you'll have to bite the bullet at some point, an english speaker will have some trouble learning the nuances of the perfect and imperfect past in romance languages by examples alone.

- Meanwhile, on top of not actually teaching you proper grammar they like to mix concepts in the same lessons, because otherwise it wouldn't be confusing enough. For instance the Portuguese subjunctive course contains examples that are actually imperative but "by chance" happen to have the same form as the subjunctive. Because obviously the subjunctive is so trivial that you have to spice things up by adding a completely different tense in there.

- The actual vocabulary they teach you is absurd. You can do the entire tree and not know how to say basic stuff, but you'll be able to say "the painter opens the power outlet" or "my tiger ate my pillow". Those are real examples.

- Worse than weird vocabulary you also have very confusing sentences. For instance take a look at this: https://www.duolingo.com/comment/2121481$from_email=comment&... "Se nós nos encontrássemos mais vezes?" which is translated by "If we met more often?". What does that even mean? It's not even a full sentence. And that's for the past subjunctive lesson, you know, that trivial thing that definitely requires trash sentences like those. And it's been there for 4 years judging by the comments, so the authors of the course stand by it.

- These types of weird sentences are super common and they keep you wondering if you're not getting an idiom of the language or if it's just a super weird sentence. 90% of the time it's the latter.

I don't understand why Duolingo is so popular, IMO Memrise is massively better. It's a lot more focused, it only pretends to teach you words and simple phrases, but at least it does the job. If you want to learn a language buy a good grammar book, a dictionary and drill vocab on Anki or Memrise. Use something like lang-8 to practice your writing. Forget Duolingo.

I do enjoy their "Duolingo Stories" service though, but there's not enough content there to keep you busy for very long and there's no "replay" value.