I read this to my 6-year-old, and we were both mesmerized. The story is told exceptionally well. First there is some "action," then some history, then more action. Practical details about rockets and space travel will fascinate kids and adults alike. And after reading this book, no one will forget the meaning of the words, "The Eagle has landed" and "That's one small step...." It sounds silly, but I actually got choked up at the climax (moon landing).
This is a great book for any kid interested in the original development of the space program, up to the first walk on the moon. I can't make a pronouncement about the reading level (maybe third grade?), but you could read it to a 5-year-old, and I think even most adults would like this book. I'm going to be looking for other books by this author.