This is a classic story that I had heard a lot about before I picked it up.
I love the Studio Ghibli animated film Arrietty which is based on it.

As a children's book this has a premise that stirs imaginative possibility. At the very start of the story it is mused that all the lost little things that you just can't find any more must go *somewhere* and the idea that little noises made in the walls of old houses might be a society of tiny people is one of those things that seems improbable, but that one continually encounters hints of.  A rustle in the evening could just be hot embers settling, or the beams shrinking, or mice.. or someone tiny falling off their cottonreel chair...

As it was published in 1952, some of these things are a little dated. The way that these families are named and the stories of the different families reinforce the ideas of classism, snobbery, and there being the Haves and Have-nots. The main boy in the story is raised in British Imperial India, and is convalescing in the English air. One of the mentions of a woman in curlers, likens her to a gollywog. It's not how that would be expressed today. * *grimace* * 

I did love the way that things are described. Even little observations like how a child's pet ferret seems to flow out of his pocket, or the ridges and shades of a person's ear, feel simple and yet relatable, and provide texture to a world seem from the eyes of children, and a world built in miniature. I'm also always sucked in by the enthusiasm of reusing and repurposing things. I guess I'm a maker and scavenger at heart.