I've been studying Vietnamese for over 2 months, and the bulk of my daily learning is done through mobile apps. But can these really teach you another language? Or are they just gamified gimmicks? Here are my impressions of the apps I've used:
Duolingo (about $80 per year for a premium subscription) - the 800-pound gorilla of language learning apps, Duolingo has a lot of things going for it. The app has a free ad-supported version, and it covers more languages than other programs. It also has a clean interface and the best gamification hooks around (there's a powerful compulsion to keep your daily "streak" alive and not get "demoted" from your current level, even though those concepts are totally arbitrary).
On the downside, Duolingo's Vietnamese content is relatively sparse. Most of the exercises are simple "choose-a-word" tests that don't really teach you much beyond vocabulary, and the lessons are devoid of actual instruction - you are left to figure out grammar rules yourself. Finally, I haven't seen any pronunciation drills, short stories, or other activities as you might get with more common languages like Spanish.
LingoDeer (about $160 for lifetime subscription) - LingoDeer's Vietnamese program is very much like Duolingo's - cartoony graphics with a lot of word-choosing puzzles. The difference is that each unit has a "Tips" section that explains the grammar rules at work, like how to form questions and explanations for idiomatic expressions. Unfortunately, for Vietnamese, the units only go up to the beginner level - there's no intermediate-level (CEFR Level B1) lessons.
Drops ($30 per year for Premium) - Drops is a simple but fun vocabulary program that mostly has you match foreign words with images. The app doesn't use your L1 language to teach, except to verify the meaning of a word when it first "drops." It's a neat idea but the app makes no attempt to teach you grammar or sentence-forming. Given the limited scope, I think the premium version is overkill. Just use the ad-supported version.
Mondly (about $90 for lifetime subscription) - If you're on a budget and need an app that does a little of everything, Mondly is a good choice. There are a variety of word-construction quizzes and even some speaking drills, though the voice recognition can be wonky. The only problem is that it's a jack of all trades and a master of none - everything it does is accomplished better by one or more other apps.
Falou (about $45 per year for premium subscription) - This is by far the best app for speaking practice, short of going live with a native. Falou uses word-by-word voice recognition that's often smart enough to detect when you are messing up your pronunciation (Vietnamese is notoriously difficult due to its six tones). Every lesson is presented as a dialogue, covering common topics like talking about your family or hobbies. The major weakness is that there is little in the way of word recall or construction - you are just repeating what the app tells you to say.
Rosetta Stone (about $180 for lifetime subscription) - I'm old enough to remember those Rosetta Stone kiosks in the mall, and I tried out the modern-day app. Rosetta Stone uses absolutely none of your L1 language, and expects you to pick up grammar and even word meanings from images and sounds. While it's an intriguing premise, the app costs a huge chunk of coin for the lifetime subscription (and the free lessons are very limited), so I passed.
Transparent Language Online (about $250 per year for subscription) - My local library provides this app for free to patrons, and I think a lot of schools and other institutions do, too, which is probably why it costs so darn much otherwise. Transparent provides a huge variety of exercises, including nifty ones where you have to listen to the speaker and pick a response entirely aurally. However, a lot of the exercises are tedious spelling games, and the Vietnamese audio pronunciations provided by the program are clipped and low quality. I wouldn't pay any money for this, but I'm glad it's free.
Pimsleur (audiobooks - $85 for the whole course) - Pimsleur offers a single beginner's course in Vietnamese consisting of about 15 hours of audio-only instruction, with some reading practice at the end. The course uses spaced repetition and constant speak-and-repeat drilling - perfect for listening to in the car. The big downsides? It is non-interactive, the written portion is an afterthought, and you don't learn all that much even after 15 hours, since by design there is a lot of repetition.
Conclusion
So which of these would I recommend? Well, they all have their pros and cons, and if you're serious about learning a language, you should probably use a combination of these, along with good old-fashioned books...more on that next time.
