The app works well as a way to watch videos for a course. It does seem to have some issues rendering the questions shown during a video. I havent tried taking a quiz with it and probably will not. The app itself is probably 3 stars.
Im halfway through my first course, Machine Learning. The content is very good and Ive learned a lot. The material is challenging and many times the videos have not been enough to be able to complete the programming assignments. However the course has tutorials and extra datasets to help debug your code. 4 star course content.
The submission portion of the programming assignments is the best. You can submit multiple times and check your progress. You get points for things that are working correctly but are not penalized for those that are not. This is important as the steps tend to build and you can make sure all functions are working before attempting the next step. 5 star programming assignments and grading.
Timle about Coursera: Grow your career, v2.2.1