This is the Norse mythology book you want your kid to read. Gaiman respects both the source material and his readers—he doesn't sanitize the violence or sex, but he doesn't sensationalize it either. The result is mythology that feels true.
It's educational without being dry, entertaining without being shallow. Kids who loved Percy Jackson and are ready for something meatier will devour this. It's also short enough (under 300 pages) that it won't intimidate reluctant readers.
The main caveat: these are ancient myths, so expect ancient values. Gods solve problems with violence, trickery is celebrated, and everyone drinks a lot of mead. But that's kind of the point—understanding how different cultures saw the world. Gaiman trusts readers to handle it, and most 10+ kids absolutely can.
High school English teachers love assigning this. Parents of mythology-obsessed kids swear by it. It's become the definitive modern retelling for good reason.