First, let me apologize at the very BOYISH ongoing theme. Although I do have a little girl, she is only two, and her tastes are formed very much by her boisterous older brothers! They are interested in dinosaurs and Legos and...well...things that smell...
I am amazed at the interest given to dinosaurs and the memory they have for dino-details. Use soap when you wash your hands, not oft remembered, but use the word "pterodactyl" and listen to a ten minute lecture on why that's not really the right word.
My dad got several in the series of dinosaurs by Don Lessem for my kiddos. He got these books for my older son, but they are being read to my younger son too. Every night. Each and every night. Sigh.
They are pretty interesting, actually. Enough fighting, poop commentary, and pictures to keep kids (boys) interested, and enough interesting facts to keep me from banging my head against the wall the 20th time I read it.
Of course, with dinosaurs, so much is theory and even since these were printed more discoveries have come to light that slightly outdates these books. The books do explain some of the past theories that were incorrect. I use that as a springboard to discuss experimenting, theories, research, etc.
I read this to my 6 year old, but my 10 year old still likes to listen and look at the pictures occasionally. In the front of the book it lists the dinosaurs in the book, how to pronounce the name, its size, and time and location. At the back of the book is a glossary of unfamiliar words. Most of the names have their origins or meanings explained in the book.
This is not a story book, but the author does put the dinosaurs in likely situations and describes what may have happened and what they may have looked like.
This is also not an early reader. Young children will definitely need to be read to or helped with the vocabulary. BUT if you want to motivate young paleontologists to read on their own, this is a good series to dangle in front of them.
I would say it is good for ages seven to nine to read on their own, five or six being read to. Much younger and it may be too difficult to understand, much older and it may a bit boring for more than an occasional read.
All in all, a nice series. Informative and entertaining.