Yes, there were a few points that strictly speaking would weigh negative in raiting this book. For once it tooks ome time till the characters got enough depth to make them easily distinguishable. At the beginning there were just two men and two women and I had a hard time remembering who the married couple and who the wife's brother and sister were. Then some of the twists were somewhat foreseeable and towards the end the culprit was easy to guess.
On the other hand it is a classical whodunit after all and you're meant to guess there (and unlike some other crime-novels he wasn't wearing a flashing neon-sigh saying 'I am the bad guy' over his head...it's just that after reading enough of these kind of crime-stories you know for which signs to look). Also the twists were probably much more surprising when the book was published in 1932, but since these type of stories were, and are still, so popular it has all been copied a thousand times it does make it seem terribly worn-out, today.
But to tell the truth: I didn't really care because the rest of the book was just so amazing and also really funny. All the characters were quite witty (and perhaps even a little bit genre-savy) about living in a possibly haunted house. Sometimes it even felt as if Heyer was parodying the genre a tiny bit while still writing a very good story, set in that genre. Also, while the characters did start out quite flat, they quickly grew on me, once they developed some depth and I'm a bit sad that it was just a stand-alone novel and we won't see them again.