JujuLeCaribou, Thanks for taking a look. (I think your moniker, JujuLeCaribou, is great, by the way.)
. . Okay, to gain a more informed opinion I have spent a week at the duolingo site working at French and Spanish. These I studied 30 and 50 years ago, respectively, so I'm not trying the site as a total beginner in these languages, which might be preferable. (If I were to start a language there ab initio, it would be German. But 3 languages at once would be too many for me.)
Basically my impressions of the site have not changed:
* the synthesized speech would not be good for a pure beginner, but it is adequate--actually, very useful--for review.
* the "lessons" provided are a good, graduated introduction to a language. They are very bare bones, but as much reinforcement as needed is given through online quizzes. And if the pace should be too slow, 3 chances are offered to "test out" of a lesson, so that a learner who truly does know the material can advance more quickly. Also one can drill materials learned earlier or quiz vocabulary at any time. This is all great for review. And one need not go through these lesson sequences to use the materials discussed in the next bullet.
* the translation of real-Web materials, such as from wikipedia, which is the purpose of the site, can be extremely interesting. The material is mainly written input however; sound is provided only sentence by sentence, and it is synthesized TTS. One cannot (so far as I have seen) listen to an article straight through. Some of the translation, indeed, is deadly dull--for instance when translating, bullet by bullet, the names of the works of an author or composer. Feedback about translation is of variable quality--from very informed to idiotic. But anyone who likes reading wikipedia articles will probably enjoy this translation.
People who do not mind learning or supplementing learning through the grammar-translation method will get a lot from duolingo. Those who don't like that method will hate the site, as it is basically an automated set of grammar-translation textbooks w/ a virtually infinite series of exercises, as well as a graded reader w/ feedback. It aims at developing translation rather than listening skills.
Probably its main defect is the TTS audio. In this regard it ranks above a plain textbook but LingQ has it beat by a mile. Where it shines is the translation setup, and its almost limitless drills, which are great at catching spelling mistakes, etc.
Personally, I'd like to give German a try at duolingo when I have the time (i.e., after I "finish" either Spanish or French there). It would be a better test of the site than is the review I am doing now. But I would start elsewhere to learn proper pronunciation, and I'd return here to LingQ for concentrated, pleasurable listening.