I practically devoured this novel.

It's written in a distinctly conversational style that I think works really well - the narrator is quite covert, and changes throughout the novel, as does the implied reader. Despite its heavy subject matter, the novel is full of a wry sense of humour. 

Otsuka has an apt perception and is a brilliant observer - I was drawn into the novel right from the beginning, which starts with the community of an underground swimming pool - the titular "Swimmers", describing their rules and eccentricies.

A great read.