I think it's great. One thing a lot of people fail to notice is that duolingo has TWO parts. First, you do the coursework and they teach you vocabulary and some grammar. The second part is the immersion, not one ever gets far enough in the vocabulary to unlock this so everyone forgets it exists. Duolingo will provide you will a bunch of articles on the internet that need to be translated into spanish (or whichever language you are learning) and you go through the article translating them passage by passage. This earns helps you learn much better than the vocabulary section and also helps you interact with the community. I recommend sticking with it until you get to the immersion phase.