It occurs to me that there are perhaps three ways (three criteria on which?) to review a novel.

The first is whether it is entertaining. 

The second is on what it says. It seems to me that a lot of reviews are based on this. Thus a novel can be hailed for opposing slavery (Uncle Tom’s Cabin) or exploring the iniquities of the Married Woman’s Property Act (The Tenant of Wildfell Hall) or for giving a voice to disaffected teenagers (The Catcher in the Rye) or for giving an insight into Igbo culture (An Orchestra of Minorities). This is what agents and publishers mean when they say they are seeking under-represented voices to become authors; they want people who will explore new aspects of life. Oliver Twist attacked the workhouse system. 

The third is on how the novel is written. Are the characters believable; are they three-dimensional? Is the plot well constructed? Is the pacing appropriate? Do the descriptions give a sense of verisimilitude? Does the writing style make a positive contribution to the feel of the book? This third dimension is what I focus on in my blog.

Perhaps there are more than three types of review. Any suggestions?

And which if these ways is most valid? Or should a comprehensive review incorporate all three of them.