A page to review any language learning resource that you've used. When it comes to resources that require money these reviews can be especially helpful for deciding whether or not to purchase/subscribe.
Very easy to use: at its heart it's essentially a matching game
A good place to start and learn your first few 100-1000 words and get a feel for the language
Gamification helps mitigate against boredom
Wide range of language courses
Can get boring and repetitive quickly
Too many ads on mobile version
Inconsistent quality of courses across different languages
The mobile app is agreed to be largely inferior to the browser version; if using on mobile, it's recommended to instead use your mobile browser rather than the app itself.
THIS IS NOT TO BE USED ON ITS OWN! Duolingo is best utilized as a supplement to drill vocabulary, and in terms of learning a language, it is ineffective as anything more than an easy-to-use tool for dipping your toes into a language.
A few courses are infamous for being low-quality and largely abandoned by its (community) developers, such as the Navajo, Hungarian, Hindi, and Hawaiian courses; keep that in mind when using Duolingo for these languages.
Has a very good import feature both on the website, and as a browser extension. You can import webpages, pdfs, epubs, and upload audio as well.
Useful tool to get you reading and listening to engaging content
$10 USD per month
User generated content is difficult to navigate. It is difficult to navigate your own content as well.
Free alternatives like LWT available
Not really a pro or a con, but it is so easy to translate text using LingQ that you can fall into a trap of over-translating and not trying to decipher a word or phrase based on context which can hinder your progress.
You can achieve a similar experience without having to import or upload anything by using a translation extension in your browser. See: Simple Translate , Google Translate
Fairly easy to use: just play the audio files
Generally quite effective for teaching grammar without focusing on the boring side of grammar too much
Covers the majority of popular languages
Expensive -- full courses can run in the hundreds of dollars
Free alternatives like Language Transfer available
Michel Thomas is primarily focused on establishing a solid grasp on practical grammar.
Michel Thomas is dead (RIP), so he'll likely have a hard time being offended if you pirate any of his courses
The languages taught by Michel Thomas himself (German, Spanish, French, Italian) generally have more courses and are higher-quality (though that isn't to say that the rest are low-quality)