Review of Duolingo plus Tips - Kann man Sprachen durch ein Spiel lernen?

Duolingo's mascot, Duo.

Hallo, und Guten Tag. If you're curious, the title of the post means "Can one learn languages through a game?". I wrote it in German, of course, because that's the language that I am mainly learning though Duolingo right now. I'm going to give you the answer straight away. Yes, as long as you know what you are doing. You can't learn perfect German (or Spanish, or French, or Swedish...) by just clicking the "Learn This Language" button and mindlessly clicking through the lessons. I will discuss why later on, but let's start by talking about Duolingo itself.
Duolingo is a free, no-ads website designed to teach you how to read and write in a foreign language. I mostly say read and write simply because the listening and speaking parts are not good enough in my opinion to be considered good practice. From this point on when I say "German" you may mentally replace it with whatever language you care about.
When you start the site for the very first time you will be greeted by this page:

The Duolingo homepage on a fresh German "tree"

If you are a beginner, you go to Basics One and start learning with very basic excercises:

The "Basics" lesson chooses to teach basic grammar rather than just giving you survival phrases. The first few words you learn in the German tree are man, woman, boy, girl, child, water, bread, apple, a/an, and the various forms of "to be", "to eat" and "to drink". However, a common phrases section comes shortly after so you can learn your gute Nachts and your gern geschehens.
If you are advanced or at least know some German, you can complete a placement test where Duolingo will evaluate how much German it thinks you know. I tested it on a second account I made just for the purpose. Its estimates are very low (to be precise, 88 skills off where I actually am on my main account):

The results of a placement test I took.

As you advance further down the German tree, as Duo refers to its course as, the sentences get more complicated and you introduce new tenses, grammatical cases, vocabulary lists, etc. As you work your way down you might get confused. If you don't get something you can click the discussion button once you've attempted to translate the sentence:

The discussion section of an early Duolingo sentence, where you can see that A. people will make jokes about the sentence and B. that people will ask for help and recieve it from fellow users. (the font changed because I'm on my main browser and I use a font changer with Duolingo. The older one is the real Duo font)
There are also audio exercises, where you listen to a sentence and transcribe it into German, and speaking exercises, where you have to speak a sentence (either from reading the German off the screen or by speaking the German equivalent to an English sentence which is onscreen.

German audio exercise

German speaking exercise

After completing a skill, it will turn gold on your tree. After some time, Duo will ungild this skill and ask you to review it to keep words frisch im Kopf. There is also a general strengthen option to go over your overall weakest words.
App
Duolingo has an app available on Android, iOS, and Windows Phone. I only have personal experience with the Android version.

German tree on the Android app. (Samsung Galaxy Nexus, Android 4.3)

Right answer in the Android app (Samsung Galaxy Nexus, Android 4.3, Esperanto)

The Android app uses cartoon images in place of the website's stock photos. (Samsung Galaxy Nexus, Android 4.3, English tree from German)

On iOS (pictured) and more modern Androids than mine, the cartoons are more widely implemented.

Screenshots of the Windows Phone App.

Essentially the Duolingo app works much like the website. The main difference is that on the app you cannot access the Grammar Notes or the Forums. On the app, there are also "word-matching" exercises and versions of the standard translations where the words are on the bottom, scrambled amongst useless words, to avoid the hassle of smartphone typing. On iOS, you may get a question where you have to choose an appropriate response to a question.

A "unscramble" exercise (First generation Nexus 7, Android 5.1.1, Esperanto course)

A "tap the pairs" exercise (First generation Nexus 7, Android 5.1.1, Esperanto course)

Why Duo is Good
-Using Duolingo is fun, and it feels rewarding. There are bonus skills which you can unlock; the Flirting skill which contains some bilingual cheesy pickup lines, and the Idioms skill where you can learn some common phrases in German. It's very gamified
-There's a great community. The Duolingo site attracts many to-be German speakers and a lot of them are very helpful. There's also some German native speakers who occasionally pop in to help in the discussion.
-Good selection of languages. While Duolingo hasn't yet added Chinese or Japanese to its list, it's got a pretty good set of languages for now:

• Spanish (Latin American)
• German
• Brazilian Portugese
• French
• Italian
• Dutch (Netherlands)
• Swedish
• Irish Gaelic
• Danish
• Norwegian Bokmål
• Turkish
• Ukranian
• Esperanto
• Russian

and several currently being developed:

• Polish
• Hungarian
• Welsh
• Czech
• Vietnamese
• Hindi
• Hebrew
• Swahili
• Klingon (not making this up, I promise)

As well, they offer an American English course to speakers of Spanish, Dutch, Chinese, Russian, Portugese, Polish, French, Vietnamese, German, Turkish, Greek, Hungarian, Romanian, Czech, Italian, Japanese, Hindi, Ukranian, Korean, Thai, Arabic, and Indonesian. A few of these languages also have Spanish, German, or French courses, and Spanish has a Catalan course.
-Immersion feature. If you feel like you want some more practice than the lessons, you may use the Immersion feature to translate real-life articles from the Internet. On account of European Union rules EU citizens may not partake in the Immersion feature. 
What Duolingo doesn't do so well
-Hit-or-miss audio. Most courses use a text-to-speech rather than a real person. In most courses these text-to-speech voices are very good. The English voice could almost be mistaken for a real person. However other voices, such as Portugese, are not very good and make it hard to hear words. The French course uses two voices, a muddy, unclear female voice and a pleasant-sounding male voice which mispronounces words (particularly pronouncing silent Es) and forgets liaisons. On the other hand, two courses have audio from a person. (Irish and Esperanto) The Esperanto voice is excellent, but the Irish voice has a bad accent and says words wrong.
For reference, listen to this English sentence:
English
then this Esperanto sentence:
Esperanto
and finally this Portugese sentence:
Portugese
-Inaccurate speech recognition. The speech recognition is terrible. You can have a native speaker say something into the microphone and it won't pass. Next you try, but midway through your attempt, you cough. It will pass this audio.
-Not enough translation from English to German. I did 50 questions (some review, some new) and marked down each time I got German to English and English to German. The results were: 44 German to English (88%) and 6 English to German (12%). This is a problem because, using Duo alone, you'll be great at recognizing words when you see or hear them, but not at actually saying or writing those same words. This unbalancing was likely done by Duolingo as a business in order to get better numbers to advertise with
-Various other questionable decisions by the company. Rather than adding the discussions and the grammar tips to the Duolingo mobile app, Duolingo has focused on adding cartoon characters to the iOS and Android apps. This is obviously to make the app more appealing, but it makes more sense to also add some stuff for advanced learners.
Tips - How can I get the best out of Duolingo?
Please note that nothing suggested here is official from Duolingo, and merely reflects my experiences.

1. Avoid using the hover-hints when reviewing. If you do, the site thinks you do not know the word well and will ungild the skill once more.
2. Do a general strengthen after regilding your tree. It will target your weakest words and keep skills golden for longer. This is the only way you can do multiple languages and not have to spend hours reviewing.
3. Ask when you're confused. If you don't understand it now, chances are that you won't be lying around and suddenly feel "Oh hey, now I understand the German case system!". There are discussions and forums for a reason.
4. Use the website. The app simply is not good enough to learn a language from
5. Do the reverse tree to your language. What I mean is, if you are doing the English to German tree, also do the German to English tree when you are far down the original. You will do much more translating from English to German and the discussions will let you see Germans writing German the way they would, giving you a better sense of how to use the language.
6. Speak with natives. The only way you can really learn the intricacies of German is speaking with a German. Simple. 

In conclusion, Duolingo can be very useful to learn the basics of a language, and you can even get quite good at the language if you know what you're doing. I have only discussed the basics of Duolingo, you should check out the site to see more of it. Anyway, bis später. Tschüss!
-James

Add me on Duolingo: Dave_Hays. I will add you back.