It's hard to believe that the same person wrote I Capture the Castle and 101 Dalmations. Yes, both were made into successful movies, but I'm pretty sure the resemblance ends there. Smith was a successful playwright before moving into novels with I Capture the Castle in 1948. It's a terrific story of a blocked writer and his family--including two daughters who have a Jane Austen-like marriage plot. The opening line: "I write this sitting in the kitchen sink" is enough to hook the reader in, and the narrator (and second daughter) is a consistently engaging voice. A writer herself, she and her younger brother conspire to break her father out of his writer's block while she and her older sister and stepmother work on the courtship story as well. The allusions to Austen are pervasive, but the novel also meditates on modern fiction, poetry, and the place of both ritual and writing in modern life. My copy came off the table at Barnes & Noble where they put things they're trying to move for summer (3 for the price of 2), with a blurb from J. K. Rowling on the cover, but other than the romance of the crumbling castle there's little to connect it to Rowling. (I just noted that Amazon recommends Stella Gibbons' Cold Comfort Farm and Elizabeth Goudge's The Little White Horse for fans of Castle, and that seems just right...)
101 Dalmations (1956), on the other hand, Smith's first novel specifically for children, is--how can I put this kindly?--not as engaging. The limited omniscient narrator gives us--mostly--the point of view of the Dalmation parents, Pongo and Missis, and they are a pretty twee pair, honestly. Pongo is, we are repeatedly told, one of the brightest dogs in Britain (not only does he understand human language and concepts like right and left, he can read English as well), while Missis is more Barbie-esque: cute but dumb. Pongo's feelings for the surrogate parent-dog, Perdita, apparently caused Smith some concern--when Missis can't nurse all fifteen puppies, the Dearlys (their owners) fortuitously find another Dalmation mother who has lost her puppies to nurse half the litter, and Pongo, we are told, thinks of her as their second mother--though not as his second wife but rather a beloved younger sister. Yeah, because I was worried about that. Well, obviously she assumes kids would be, but it's a bizarre detail to go into, isn't it?
Throughout, the dog characters are far more interesting than the human characters, but it's really the secondary characters--the spaniel whose owner is too elderly to go out, the sheepdog whose charge is a two-year-old boy--who are the most intriguing, while Pongo and Missis seem like pure stereotypes: self-sacrificing parents, the strong handsome male and the loving beautiful female. There's an implicit pro-animal-rights message, of course (the bad guys are all about fur), but there are some big problems as well. For example, the evil Cruella deVil is consistently depicted in stark black-and-white, as if to suggest that the polarity itself is evil. But the novel engages in the same kind of polarity--Dalmations good, Cruella bad--reinscribing the black-and-white worldview that it might have seemed to reject. And don't even get me started on class, both with the treatment of servants among the humans, and mixed breeds among the dogs (we are told they're just as lovable as the purebreds, but we don't meet a single one).
Monica Edinger had a great post on animal fantasies a week or so ago in which she asked commenters to consider what makes a good or great one. I'd say this one uses the animals mostly as humans stand-ins (they marry, eat human food, read, and communicate in sophisticated ways--although that latter caveat may simply reveal my species-centrism) and the kind of humans they stand in for are rather simplistic and stereotyped. So, not great.
It's a quick read, and I remember enjoying the animated movie as a kid, but it's not in Castle's class. There's a sequel--The Starlight Barking--but I think I'll skip it.