Nice product. Used it for a book about economics. The questions are good and tackle the main points and messages in the book. It helped me remember some parts of the book that I completely forgot.
I started to test this tool to see if it can help me to prep for my CFA Level I certification. It's precisely what I was looking for! It provides random questions from the entire CFA Level I set, and I'm amazed at how seamlessly it fits into my study routine.
Useful thing to have it ask me questions about a book I read! It refreshes my memory before going to watch a movie adaptation of a book. Of course you can use it before an exam or a job interview. The app is well made, it is easy to sign up and use. Buying credits is also seamless.