5 stars: The main two things holding back people from progressing in language to the Advanced Level are grammar and vocabulary. This is a great tool for daily practice of vocabulary. Pretty cheap lifetime membership. I have taught French and Spanish for ten years. I like it. With Premium it has recall at intervals that are easier to memorize.
4 stars: Overall it is very good at helping me learn vocabulary. I like that aspect a lot. I haven't found a way to adjust which words come into the rotation. I feel like sometimes it repeats words I am very familiar with but rarely brings up words I am struggling with. I wish there was a way I could focus on words I need practice on.
4 stars: I practice drops like usual, and since I practice drops everyday, so I get bonus time everyday. Just now like usual, after I finished my 5 mins, drops give me bonus 300 seconds, but then the apps suddenly have a glitch, it turned off by itself. When I open again, I didn't have any bonus time! I never have a glitch before, until today!
3 stars: Help option doesn't work, they give you the run-around if there's a problem, resets streak counter randomly, shady subscription practices, won't recognize your progress across multiple devices even if you have an account. Edit: adding stars for the consistent app stability over several months, streak counter is keeping up.
5 stars: I love drops. It's a fantastic app. However, I'm regularly signed out of my account and now I can't even sign in....