Many of these review publications include Lexile (reading level) measures. About the Lexile Framework for Reading
Most newspapers include children's books in their book review sections. See the New York Times, Washington Post, and Access World News databases.
There are a lot of bloggers doing book reviews of varying quality. See this list of The 75 Best Children's Book Review Blogs for descriptions of several.
Education Research Complete, ERIC, Literature Resource Center, and other library databases include publications that have book reviews.
For those with a Pamunkey Regional Library card, the database Novelist Plus K-8 on their database page is a reader's advisor and book recommendation database. All R-MC students are eligible for a library card, just go to a branch with your R-MC ID to get a card.