Books I Almost Couldn't Finish: Death Comes to Pemberley (but not fast enough)

I'm not a fan of Jane Austen. Archaic courtship rituals and Regency attire just don't butter my skillet, and aside from Northanger Abbey (a delightful send-up of Gothic novels), I haven't enjoyed any of her work. Frankly, I read P.D. James's Death Comes to Pemberley solely because homicide and Jane Austen seemed like a damn good combination.
Wandering Coyote has already written an excellent review of this book, so I'll restrict myself to the main beef I had with this "mystery" novel. Yes, the characters are about as interesting as lettuce, and the pace is sluggish, and you have to suffer through a rehash of Pride and Prejudice.  But the real problem is this...

The key questions:

Who slaughtered a man in the forest near Pemberley? How did they do it? And why?

The questions that are actually asked:

Whatever will the neighbours think?
Are there enough savoury tarts to satisfy Sir So-and-so and Viscount Such-and-such?
Shall we take the the coach, the carriage, the barouche, or perhaps a hackney chaise?