When a book review is written by an expert in the field and is more than just an overview of the content, it may be very useful to decide whether it is worth to buy the book or to look at it in a library. Good reviewers draw attention also to shortcomings and mistakes. I always read the reviews of the books from my fields of interest, and I have written such myself. I regret that some journals stopped to include reviews.
for me the journal I will read seriously, if the journal has quality: a credible publisher, a positive format impact, according to my field of study and good structure of content. Cheers