I read a great many books, and I think sometimes that renders me a little jaded. While I enjoy most of what I read, I don't usually react with the jumping-up-and-down evangelistic adoration I lavished on my favorite stories as a child.
Not usually, but sometimes.
The House in the Cerulean Sea is one of the most warmhearted, purely wholesome and enjoyable stories I've ever read. Given that I tend to be rather grimdark in my reading tastes and 'wholesome' is not ordinarily a work I would even think to apply to most books I enjoy, I would recommend this book to anyone. In fact, that's exactly what I have been doing, passionately and at great length. I intend to beg and cajole everyone I know into reading this book, because it would be a disservice to them to let themselves be deprived of it. Don't do yourself that disservice, either.