Critics; send a private reply to the requester to point out any mistakes or issues in a book. Also, point out strong points in a book and state what makes it worth reading. Get more perspective on both sides as an author. Simply exchanging views with another writer.
Reviews; as a causal reader who recommends if the book is worth reading. It can also vary from good to bad reviews.
I promise honesty while conducting this.
Penalty; I ask you to review my book as well and leave comments within the chapters. I wish for honest reviews though.
Completion of request within two hours if I am awake but less than 12 hours if I am asleep essentially.