My daughter has been using this series in 3rd and 4th grade. She enjoys them. I like how the material is simply presented in a story-telling fashion. I find the text very engaging. I think the drawings are pretty and add to the material. I use this as a journalling exercise. She reads a section and then writes an entry in her science journal about what she read and draws a picture. And she never complains about having to do it, so it must be good! We have the whole series and there is a lot of material there, so we can use it for several years.
My 7-year-old is often reluctant to do her silent reading. These nature readers have sparked her interest so much- she can't wait to read and tell us about what she is learned. What a wonderful way for a young child to get reading practice, while also learning science! These books helped me to discover that she prefers non-fiction reading to fiction. Tremendous value!!!