Duolingo isn't as simple as some of these comments make it out to be. I can only speak for Spanish as I'm 75% done through the new tree (one more group to go). They have actual written, albeit small bite sized written lessons for every lesson branch. If you compiled all the written lessons (the bulb icon next to each lesson) you would have an introductory Spanish text book.
I also take lessons on italki and my gf is a native spanish speaker. It's a great supplement tool if you're consistent.
I also take lessons on italki and my gf is a native spanish speaker. It's a great supplement tool if you're consistent.