All right, let's go to Freddy the Pilot since it's now back in print. I wanted to start out with some summary of my evaluation, but I'm not sure I can just yet, so I'll just go straight into the details.
What impressed me most with this book was the sheer density of ideas. I can think of no other book that better demonstrates Brooks' inventiveness. There are two major continuity elements to start off with: the Horrible Ten (introduced two books ago) and the Boomschmidt Circus. On top of that, there are major threads weaving through this book involving Robin Hood, comic books and their characters, Freddy becoming a pilot, and Uncle Ben and his bombsight that turns out to be a crackerjack metal detector. Then you have little, almost throwaway bits, like the incident that Alice Tracy celebrated in her article on the Boomschmidt circus with Mrs. Wogus jumping over the elephant. It's quite extraordinary.
But on to the plot. It begins with Freddy reading about Robin Hood and explaining him to Sniffy Wilson, the aptly-named (as always) skunk. Then the Boomschmidt Circus shows up with a dilemma (or quandary). We don't immediately find out what the problem is until Freddy and some of the other animals attend the circus performance. After a brief interruption by a lawyer named Newsome (or "Nuisance," as the sheriff accurately puts it), the show is interrupted by an airplane buzzing the tent. The likely culprit is one Watson P. Condiment, who wants to marry Mademoiselle Rose and has threatened to disrupt the circus if he can't.
Freddy goes off to take flying lessons so he can use a plane to track down the base of the other plane. Meanwhile, Uncle Ben shows up with his bombsight, which is extremely accurate as long as you know where you should really be aiming it. (There's an interesting visit by a host of military bigwigs that shows Brooks' gift for satire at its best.) Next Freddy goes into town, in disguise as a woman, and encounters Mr. Condiment trying to get the local bookstore proprietor to stock his comic books. Serendipitously, Freddy manages to get Willy the Boomschmidt Circus snake to frighten Mr. Condiment just as he's saying that the "Great Serpent" monster in one of his comic books is totally fantastical. Freddy then introduces himself with the same name as one of the other characters, Lorna del Pardo (otherwise known as the Leopard Woman).
Freddy returns to the farm and discovers the metal-detecting capabilities of the bombsight, then takes off in his plane and tracks the other plane some distance to the north after it bombs the circus with bags of flour.
Then Freddy resumes his Lorna disguise and, with the help of Harrison the leopard, pretends to turn into a leopard for the benefit of Mr. Condiment, who is of course terrified that one of his comic book characters has come to life.
Freddy eventually tracks the plane to its home base and, after some conflict between the skunks (who have adopted Robin Hood wholeheartedly) and the Horribles, parachute some of each onto the base. There is then a bit of a breathing space as Freddy takes each of the Beans for a ride, the military men find out about the alternate function of the bombsight and fight over it, and Newsome pays another visit to the circus.
Things pick up again as we move to the secret air strip, where the skunks and Horribles burn up the airplane used to terrorize the circus. Freddy then shows up in his plane but is quickly captured, and Condiment's assistants take his plane as Condiment and Newsome continue to plot. The skunks and the Horribles manage to turn the tables, driving Newsome away and capturing Condiment. However, the assistants return after stealing the bombsight, which they use to find and then release Mr. Condiment. A pitched battle for the house ensues and ends in a stalemate with Condiment guarding the outside of the house and Jackson, his crony, going for assistance.
Then the cavalry comes over the hill in the form of Mrs. Wiggins, in disguise as Condiment's comic-book Demon Woman, and her chauffeur Uncle Ben, who frighten Jackson away. Then Condiment, confronted by yet one more character from his comic books, basically gives up and signs a confession.
Then we come to a sort of epilogue, where Boomschmidt has to be told by Condiment that Rose is in love with him and wants him to ask her to marry him. (Have I gotten all the pronouns right there?) Condiment is given his freedom as a reward for this revelation, and the wedding is held at the Bean Farm. And all is well.
Whew! I have a feeling that's the longest I've taken to summarize the plot, just because there's so much going on. I haven't even mentioned things like the cows laughing hysterically at the comic books and other little throwaway bits that are in here. So it's quite a feast.
On the other hand, the ending seems a bit contrived. Condiment seems to give up rather easily, though admittedly I don't know what it would be like to be faced with Mrs. Wiggins in full makeup. And the whole business with Rose and Mr. Boomschmidt seems out of character for the books, as others have noted, wondering if perhaps Mrs. Brooks or someone else suggested that plot point.
I think also that the characters are so busy that we don't get as much of a feel for them as characters, except for the occasional fun bits like Mr. and Mrs. Bean getting their plane rides and the cows laughing at the comic books.
Still, on a chapter-by-chapter basis, this has to be one of the most inventive and entertaining of the Freddy books. I suppose in conclusion that I'd put it a notch below the very best of the Freddy books, but still well up there.