Extremely useful. I have lists with thousands of words. This is how I drill kanji, I write some of my notes in here, I have created lists dedicated to certain subjects and conversations. It’s been a while since they’ve updated this app, but I use it all the same. Definitely useful if someone is wanting to study Japanese, and it’s a free alternative to anki that’s just as good. Also, no ads, no payments, nothing but learning and knowledge.
I wish the devs would update the app a bit to include some words and phrases like 盗み入り、メシウマ、行目、係決め、班別、which I’ve heard but seem to be more obscure.
However, it’s a great app