I had a hard time deciding what to rate this, and I think it might really be more a 3.5.
It's a fun, fast-paced little book for what it is. Which is, really, more of a children's book-- why this isn't shelved in JFIC or at least YA I don't know. It feels a lot like a modern take on THE NEVERENDING STORY, but with a great deal more mythological diversity.
There are some extremely slow parts in the middle, but for the most part it's a fast-paced and witty book that would make a great read-aloud for kids, maybe ages 5-13?
I liked it, and I don't regret reading it one bit. The cover art is gorgeous.