It’s never a great idea to read reviews of a novel before you read it. It can distort your unique experience. In the worst instance, a review may even betray some of the plot. However, if you review a book without looking at other reviews then you may speculate about something without having had the benefit of the research of others.
A pertinent example of this was when I reviewed ‘Nora Webster’ by Colm Tóibín. I had no idea of the autobiographical elements in the realist novel. Hence I overestimated the importance of the influence of Joan Didion on his narrative. Both texts involved widows disposing of the clothes of their husbands, but because I read one after the other I imagined an influence to be significantly stronger than it was in reality. My original feeling was compounded by the flattering review Tóibín had given to Didion.
Hence it might be best practice to look at other reviews before you commit your ideas to paper. However, that approach could compromise your originality. In the end, the weight which you give to the findings of others depends on the purpose of your review. And every reviewer will have their own motivations. In other words, a book review is not a scientific enterprise and there is no one way of producing one that will satisfy all readers.