Heed the warnings for this one because this gets dark:(show spoiler)
I was worried after the last couple of books that this series would end with a whimper instead of a bang, but thankfully I had nothing to worry about. And I can reiterate, definitively, that book 4 can be skipped as everything that's revealed there is brought up here - not in every detail but enough to know what you missed. I was also worried I'd have to endure more of Freddy and Mikey's POV, but thankfully that didn't happen. Sadly(show spoiler)
but I can deal with that when I get there. I was hoping to see(show spoiler)
The big showdown with the Duke has come at last and it's just as messed up as I'd thought it'd be. I got so angry at Freddy and Mikey multiple times, and I still can't really buy their relationship - and thus Freddy's motivation. I'd more easily believe that Freddy's pride was insulted by his dad presuming to take a plaything away from him than I do that he actually cares about Mikey but whatever, it was a smallish part of the plot and not lingered over too much.
It was neat to see Windsor take a more active role in the story, now that he's a little older and learning new words. :D Lawrence and Quentin are put through the ringer in this one though and it's often difficult to read because all their weaknesses are used against them. Both of them have grown and changed so much since the first book and their adventure here tests all of that growth to its limits. I really had no idea how this was all going to be resolved, which just added to the angst and intrigue.
This was a wild ride and once the action gets going it doesn't really let up until the end. It was hard to put down at times and it went quickly. We get a nice little epilogue that hints at what the next arc is going to be dealing with, and I for one will be eagerly awaiting that release.