My kids love it.
Admittedly, I haven't read all of the book. I have read the first half, and it opens with some sadness. But as my 7 year olds warned me, "Dad, you won't like the beginning". So, he knew it was sad, but like most 7 year olds, can take a lot in stride. These are the first books (as I write this, there are 5 in the series) that my kids can't put down. One of them has read each of them 10 times. There isn't a lot of text, as it is a graphic novel. Some of the images/drawings are a little scary, but when your kid is to the age they can read it, I think they'll be fine.