I'm currently using Duolingo to learn Portguese. I've found it to be a very effective way to build up a basic vocabulary and grasp the pronunciation. I plan to start to in-person classes in a couple months once I know ~1000 words. It seems about as effective as anything else to me. In my experience learning a new language is almost entirely about how much effort you put in, rather than the method.
One thing that strikes me from these comments is that many people become focused on completing the exercises and getting points. I can see that could happen, it requires a conscious effort to make sure I understand every sentence and say it out loud.
One thing that strikes me from these comments is that many people become focused on completing the exercises and getting points. I can see that could happen, it requires a conscious effort to make sure I understand every sentence and say it out loud.