I think it's really more a 4.5 but it's a great read. Now I need to go brush up on some of the pantheons.Reading it a second time now as part of the #1b1t thing on twitter. Also learning more about the pantheons :-). And reading Anansi Boys alongside this time.
Added June 14, 2010:
Finished it this weekend; enjoyed it even more this time. The #1b1t discussions helped me find a lot more depth in the story.