Stodgy at first, with a main character who is maddeningly methodical (and effective), and whose motives are never fully immediately clear - not even, perhaps, to himself. Actually, this book is quite stodgy and stilted nearly all through, yet this very stodginess comes to define and exemplify our protagonist, nay, to embody him -and the nacre shell he has created to protect himself, from what?
At times it seems almost as if the author is trying too hard NOT to write to young adults, her usual and primary audience. That being said, read it - and then RE-read it. This book is not at all geared to young readers. It's also a book which is even more enjoyable on a second read. Knowing the ending at the beginning - and the twists therein - makes this book feel like a conspiracy between author and reader, which is thoroughly enjoyable! Being privy, as the story unfolds, to the ironies of Gregor's relationships with almost all the other characters gives the story a delicious edge of hilarity.