After a strong start and solid middle, the ending was a letdown for me. It felt overly simplistic and the last 25 pages were almost a chore to read. I considered between giving 3 or 4 stars - it's really just the last 20-30 pages out of over 300 that disappointed me, but the impact was still enough to make me lean towards 3.
The setting and set up, as I've come to expect from Yokomizo, were superb. (In fact, if it wasn't for the fact that I have high expectations for his novels, I might have given 4 stars.) I'd still recommend this book to someone who liked his other works, but it doesn't come close to i.e. 獄門島.