4 stars: Well this app is great for learning nouns, not so much grammar and stuff. But one app can't do everything. The five minute limit is kind of annoying, every ten hours you get five minutes. I do like the color schemes and stuff, though; very visually appealing. I also like how it slowly teaches you a word, first with the translation, then with a picture, then no translation, etc.
5 stars: Much Better than Duolingo for Vocabulary. I wanted to learn some basic vocabularies and tried other app for few times until I found this app much better both interface and the algorithms in categorizing words. There is only some minor issues like not being able to delete the words you added to your library by mistake.
5 stars: Great app for increasing vocabulary! This is actually my favourite language learning app because it teaches you words by repetition.
5 stars: Drops really helps! The way it pronounces, shows, and allows you to learn in a fun way helps you learn a lot on the way. I've had this app for a while now, and ever since I got it I've been able to read a few words on my own now. I suggested this to a friend who wanted to learn French and they agree that it indeed helps.
5 stars: Super impressed. I've made major improvements in my vocabulary since I downloaded the app. I sprang for premium (I think it's cheaper to buy on the web instead of the app) and it's been worth every penny. You have to work on it everyday though! I would recommend.
4 stars: Wish ...