Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great solved problem reference, as advertised, nothing more

This is a good repository of standard undergraduate QM textbook problems and worked solutions. Worth it's price as something to add to your arsenal of solution manuals to get you out of jams when you get stuck.If you are unclear on QM principles and need more than practice problem solving, you would be better off looking at a concise text like Griffiths undergrad-level QM book.