Ashleigh I read it in high school even though it was way below my reading level. I am an adult now and I still read young adult books because they're clean.
Daylightdarkness I read it about second grade. (I was an advanced reader, about sixth or seventh grade level at the time) I would recommend it for anyone who enjoys sassy fantasy books, but the target is probably about 3rd-sixth grade girls. Very strong female main character.
Toni I would agree, written for 3rd-6th grade. I enjoyed it as a quick read as an adult though. It is light and lovely.