"A Good Spinoff sans Percy"
This was a great way to introduce new characters to an already successful series. The new spin - hinted at throughout the book - and revealed at the end is an interesting angle and should produce more great reads.
"Let down ... my own fault"
First, the book is very good. I listened to the first two and waited anxiously for a few months for this release. My let down is from presuming this series was a trilogy. Arghhh! Three more books to wait for! It was the same with Harry Potter ... worth the wait but the time between volumes passes slowly.