This entire trilogy is a gold mine for those of us who are fascinated by Q. Unfortunately, it is probably not going to appeal to those who find Q annoying, or those looking for a classic Picard-centered adventure.
However, having said that, this book is my pick for the weakest of the 3. Q has shared a part of his history with Picard, attempting to convince Picard to stop the Enterprise-E from making a big mistake... but they return to the Enterprise too late to stop it. With the release of a superbeing that makes Q look like Mother Teresa (well, maybe not THAT nice, but you get the idea), Q shows that he is far from being a perfect being. In fact, he gets scared right down to his socks (do they wear socks in the Continuum?) Admittedly, even though this does give a great insight into the basic character of Q, it doesn't make for very pleasant reading.
Also, this book can seem rather disjointed at times, since Q and his enemy tend to flash all over the ship during their battle, and because there are other problems facing the Enterprise-E.
All in all, a nice wrap-up to the trilogy, but perhaps in need of a quick re-edit.