The cons: Inadequate or nonexistent explanations of grammar. Constant interruptions for silly medals or leagues. Learning a language is not a competitive event. It's pragmatic self-improvement. I. Don't. Care. About how I'm doing compared to anyone else. Amateurish, garbled voices with terrible enunciation. You can replay at full volume, and still not be able to make it out. Constantly having to redo a question because of a single trivial error in a long complex sentence. Pros: Beats me.