It's a good app, but, it's too strict and precise on words like "the" and such. Most people wouldn't care if you said das or die in some situations. Also, the ads and heart system constrict the learning, by denying effort, you only have failure. I understand the ads for funding, but get rid of that stupid heart system man. A simple typo or mistake can make you done for the day or week because of the heart system.