First off - if you are new to the series, don't start here. You'll probably be turned off. However, if you are a fan, this is a must read. Don't expect the bouts of gut-busting laughs and tender moments though - this is a purely average bit of work.
The authors/publishers broke tradition in that this is not a Myth book from Skeeve's perspective, but from Aahz's. While this has been done before of course, the standard that was set was that any book from a perspective other than Skeeve's would be a M.Y.T.H. INC title, instead of just MYTH. A minor point, but it shows a disturbing lack of detail that occurs throughout the book.
My main pet-peeve though was the constant stream of typos and over-all bad editing in the book. Whole sentences are dropped after the first word, quotation marks are missing half the time so you're not sure whether someone is talking or it's just narrative, whenever there is supposed to be a hyphen is supposed to be used, they use an apostrophe, and there are dozens of times when a word is missing from a sentence, or a word is duplicated, and so on. Very aggravating and distracting.
Worst of all though is the lack of character control. Especially with Aahz, the characters just don't seem all that dynamic, and at times are competely out-of-character. Many of the scenarios the characters get themselves into (and the ways they get themselves out) are either over-simplistic and unbelievable, or even flat-out contradict precedents of possibility established in previous books. Of course, since JLN (whom I love) joined the team, it seems like alot of things that were set down in previous books have gone by the wayside (anyone remember the rule that impressed dragons couldn't be controlled by control sticks? The authors sure don't seem to anymore.)
All in all though, it is a solid MYTH story, if poorly told. I personally was disappointed in the way the ending seemed to be sudden and short-changed, as if the authors' deadline was coming up and they just had to finish it right away. However, if you are a fan of the series, you should definitely grab this book, just lower your expectations a bit.