Well, maybe if it actually improved itself, then there wouldn't be. Sorry, I'm not a fanboy that sees no flaws it.

• No native audio (Can't learn listening comprehension, you how are you going to understand natives in real life?) (Should learn from the beginning like book courses actually do.
• Tries to teach you so many synonyms at one time, yet can't teach you the differences between them.
• Tries to teach you funny sentences, which is useless for real life like shopping, restaurant, etc.
• If you get answers wrong, it doesn't always give you the word you're actually learn, but get you a complete different word they don't teach you.
• At times in multiple selection screen, it will give you a word randomly out of the blue that has never taught you and expects you to know it.
• Uses cookie cutter sentences, rather than actual useful sentences (see synonyms.)
• No grammar
• Mobile app is so easy, because they dumbed it down so it keeps people from leavy. It takes no effort to complete a course on it.
• A lot of the courses don't teach useful vocabulary. (Spanish for English course)
• The "Discuss sentence" is filled with more jokes than actual useful comments.
• "Discuss sentence" is broken most of the time.
• A lot of the courses are subpar.
• Courses don't teach colloquial sentences.
• Vocabulary is not consistent throughout the course.
• Mobile course is useless.
• The SRS system is poorly done. Trying to learn German adverbs and a lot of the vocabulary, but can never remember it because I'm not taught it a majority of the time.
• No context is ever given
• Trying to understand the TTS used is hard a lot of the time, because it's a robotic voice.