I just read this book recently and loved it. I'm amazed people haven't been collaring me and saying "Have you read Growing Up Weightless yet? It's fantastic!" It's the sort of book that ought to have a cult following.
It isn't really a coming of age book, it's more complicated than that. A lot goes on around the edges, and much that you think is important, isn't. This book is best read, in my opinion, in one or two sittings where you are really paying attention, and taking five minutes to process and then turning around and rereading to see what bits you missed the first time isn't out of place, and is well-rewarded.