I used Duolingo for about a year to learn Portuguese but I recently switched to just taking a course I bought on Udemy.
First let me say that Duolingo is great for learning vocabulary but unfortunately that's it's only strength. The problem I realized after starting the Udemy course is that Duolingo teaches you the words but they seldom teach sentence structure or the "glue" between all those words you learn. So you get to a place where you know a ton of words but can't hold a conversation because you don't know how to form sentences.
With that said I would still recommend Duolingo strictly for their vocabulary. I would suggest a course to supplement learning though, not to mention it's much cheaper, the entire course cost me less than a month of Duolingo Super.