Lots of Pros. Some Cons. Details below...

I’ve tried many apps for learning Japanese, but I keep coming back to iKnow for building vocabulary. It just works. I pay $30 for a single session with a tutor, so the $7-8/month subscription is really no big deal.

The algorithms and app are FANTASTIC!! But the Japanese lesson plans are NOT FOR BEGINNERS. I really like this app - but the lesson plans have some serious problems for beginners (all of which are completely fixable if you want to take the time to write your own lesson plans through the iknow website)

The pros
1) great for building vocabulary
2) effective algorithm for spaced repetition - the best I’ve tried
3) learn to listen/say/read/write all at once, pretty interesting content (for language learning, which is generally boring)
4) ability to quickly add my custom words to my study list (via iKnow website). The custom words is way to use - just type in the word in Japanese, and iKnow adds the translation & suggests sample sentences.
5) good variety of testing modes - you really learn deeply..

Pro/Con
1) forces you to learn kanji, hiragana, katakana
Pro: if you want to become literate
Con: If you just want to speak Japanese. There are probably faster learning methods.

The cons below are only about the Japanese Core lessons. If you login to the website, you can add shared courses which are much much better than the ones provided by default.
1) Examples sentences are not suitable for beginners. The examples sentences assume you understand Japanese grammar. Even in the first Japanese lessons, you’ll be hit with intermediate grammar usage. So, when I was first leaning Japanese, it was pretty much impossible to use this app. You can’t turn off the example sentences, and must be able to type in the word to pass the lesson. No problem for nouns, but verbs and adjectives are often conjugated in the sentences. So, it’s not enough to remember “taberu” for “to eat”. You might need to understand (read/write/hear) the Japanese for “to eat, to have eaten, to not eat, to have not eaten” or even more complicated grammar. To be clear, this is just a lesson plan problem. Someone could write a lesson plan with beginning grammar in the beginning lessons… but they didn’t…

2) Words are introduced randomly (100 most common words first, etc.) This seems like a reasonable idea, but it would be much easier to learn in related groups of words. For example, learning a bunch related words together would be more useful than 10 completely unrelated words. Again, this is a lesson plan problem. Someone could organize the words… but they didn’t…

3) The examples sentences use vocabulary you have not learned yet. This would be ok if you’re planning to learn that vocabulary soon, but that’s not the case. The examples sentences in lesson 2 might use vocabulary from lesson 7 or 17. Again, completely avoidable...

SUMMARY
I think the app is darn near perfect, but the Japanese Core lesson plans are basically horrible for beginning Japanese language learners. Its basically like trying to learn by popping open a dictionary, memorizing a random word, then repeating forever. I suggest trying the "JLPT N5 Grouped” lessons instead (you have to find them on the website, add them to your courses, then they will appear in the app too)

Jeff Free about iKnow!