I have heard the controversy surrounding this series of books and the TV show it inspired. I do not care about the controversy. I have enjoyed all three seasons of the TV series, and I enjoyed reading the book that inspired it all.
There are, of course, many differences. Here are some of the big ones:
Angel Batista works for the Medical Examiner in the book. He is a detective in the TV series. Detective LaGuerta is not a Lieutenant in the book, though she certainly aspires to be. Dexter's sister, Deborah has to work a bit harder in the book to get the transfer from Vice to Homicide. Dexter's brother is not revealed until the end of the book. Sgt Doakes does not play as big of a role in the book as he does in the series. In the series, he suspects Dexter is hiding something and tails him. In the book, LaGuerta is the one who tails him, at a rather high price.
I could go on, but I think the point has been given. I will be reading the next book of the series soon. In the meantime, I have other books from other series to catch up on.