Good, but not great
However, of the 500 or so questions that I saw, there was something wrong with probably 10% of them. Some were worded poorly. Some had accepted answers that directly contradicted other questions. Some of the explanations were unclear, unhelpful (simply restating the answer), nonsensical ("...lowering the boiling point of water, causing it to freeze"), or out date (leak rates that changed five years ago).
Was it worth $3? Absolutely. Will you be frustrated at the questions? Probably.
Response from developer
We are so sorry for your bad experience with our app. Could you please use our in-app "Report Mistakes" function to help us identify the questions with wrong answers and review them? It would be of great help! Thank you so much!