This is one of those...
..."Did he see the same movie that I did?" moments. And one of his criticisms was the accent of the evil loquatious feline?
Although the main character is a total whack job, he is not a deliberate serial murderer. Rather, circumstances force him to kill, to keep his insanity from being discovered.
After the first killing and dismemberment, he places the head on a table and feeds it. Then he sticks it into his refrigerator, and -- you guessed it -- he has coversations with it. The heads of the next two victims also end up in the refrigerator, also talking. It's a hoot!
Where the reviewer went wrong was in regarding "The Voices" as a horror-comedy. It's not; instead, it's a farce, and a very well, er, executed one.