Okay, let's make this quick. Like Bandaid removal time. I thought this book was A) Confusing, and B) a Travesty. Let's start with A.
A) All of the gentlemen in Highbury, except for Emma's father, are vampires. And all of the women, except the ones married to them, are oblivious, even though none of the men ever eat, they all have "cold, pale skin" (a phrase that was oft repeated in the book), they never age, they move super fast, they are strong enough to throw cows over fences, they avoid sunlight, they have black-out curtains in their windows, and a few of their eyes change from black to blood red over the course of the book. The gentlemen's agelessness was particularly confusing. How is it that Mr. Weston is stuck at 50-something forever, Knightley is stuck at 37, and Frank is stuck at 23?? And it's not because that's when they themselves were changed from humans to vampires, because Knightley (presumably) and Frank (definitely) were both born vampires! So Frank aged along until 23 and then stopped, and Knightley aged along until 37 and stopped. *deep breath* Anyway. Plot holes.
B) By inserting all these inconsistencies and weirdnesses, the author has shown that he thinks very little of Emma's mental faculties. He's made her completely stupid, in short. I was particularly blown away by her dumbness (in not noticing that her dear friend and lifelong neighbor, Mr. Knightley, is a vampire) at the scene where Knightley declares something like, "I was thirty-seven years old when you were born." To which Emma replies, "And you are still, haha!" Hello! Doesn't that seem a tad, I don't know, impossible to you, Emma?! Why, twenty-one years later, is Mr. Knightley still thirty-seven?? So the author made Emma stupid and Harriet really fat. So fat, she can't reach the wooden stake she's tied around her thigh when she's being attacked by vampires.
So. I can only conclude that the author's purpose in "writing" this book was to show his contempt for Emma in particular and Jane Austen in general. And since I love them both, I did not like this book. That's my take.