Georgette Heyer's mysteries have interesting characters and some humor without the total silliness of her Regency Romances. I am not a good judge of how well the mystery is planned, since I tend to get more caught up in the characters, how the dialog is handled and if they stay in character, rather than plot twists. Her dialog was usually clever and moved the story along quite well. It did seem that the most unlikely person turned out to be the villain most of the time, but she kept adding some fresh concepts to the stories and I just wish she had written more mysteries and less romance novels.