I used to absolutely love this app. It's extremely useful for learning a language and I've recommended it several times. Until they added hearts. Everyone hates this system, it punishes you for making mistakes when one of the best ways to learn a language is to get it wrong until you understand and get it right. Prioritising money over learners is just wrong. I also have ADHD which causes me to make careless mistakes and I get penalized for having that disability.