There are a lot of things wrong with this as a textbook. There is virtually no grammatical explanation merely tables of accidence. The "exercises", if you read the introduction, are not really exercises at all but tests to help a teacher using this book see how their class are getting on. Only were someone to do an answer key would they be of use to someone learning on their own.
However the readings are excellent. They are a good read.
They also written to highlight the new grammar being introduced. They introduce too much grammar per chapter for this to substitute for the lack of grammar explanation but for revision this is very helpful.
As a first book I would not recommend it. However, if like me you have already completed one course and still aren't up reading original Greek this is a must have (IMHO).