I read this book with a Japanese reading group recently, and just finished it today. This was easily the most challenging reading project that I have managed to finish yet, being much more difficult than the thriller novel, the Harry Potter books, or the short stories collections I have read so far. This book was chosen because it was nominated for a special award for the year (which it lost), and while the story is interesting and has its surprises, I was kind of frustrated with it for a few reasons.
The main idea is that all these strange people are called together to a wacky glass tower mansion owned by a nasty old rich guy for a special unveiling of some mystery-related artifact. However, before the unveiling can take place, the old rich guy is murdered, setting off a series of increasingly bizarre kills in a story that drives deeper and deeper into meta absurdity.
My main issue early on in the story was that I just didn't like the characters much. The "famous detective" character is eternally with her nose in the air and spouting lines about her famous mysteries and somehow a million miles ahead of everyone else (she might be worse than Sherlock Holmes in this regard). A fortune teller lady cries and whinges constantly. Those two (and to a lesser degree maybe the police officer or the chef) made me grind my teeth, and for long stretches a lot is being set up, but the story kind of drags. Later, when the mysteries are being solved, some of the resolutions (one in particular that deals with a lock) just seemed impossible to me--like there was no way anyone could have guessed that. The big twists right at the end culminate in the book positioning a truly despicable character as somehow sympathetic, too--like we are supposed to think this person should get away after killing God only knows how many people over their lifetime.
Still, the story can be compelling in stages, and it was fun to try to piece together the puzzle towards the end. My group figured out some big parts of the puzzle before they were revealed, but certainly not everything. The meta aspects can be really fun and amusing but also sometimes come across as overdone.
Anyway, I feel pretty accomplished having finished reading!
Edited to add: I listened to the audio version and enjoyed it immensely! The reader is very talented and gives each of the characters great expressiveness. He really brought the story to life, and I enjoyed it way more than when I originally read the book on the page. I would give the audio version a four star rating.