A really fantastic setting that just happens to be an excellent sandbox, Red Tide contains strongly drawn cultures (including some really amazing takes on Dwarves, Elves, and Halflings) with inbuilt conflicts and a sense of history. There are a great variety of potential antagonists (everything from barbarian tribes to urbane blood sorcerers), and plenty of places to come from, with a strong cultural context provided for why a given character might have turned to adventuring. The book has an excellent series of tables to generate sites for adventuring - everything from a dungeon crawl to a court intrigue can be generated. The book also contains a series of new spells (all of which appear pretty solid), and some excellent advice on constructing and running a sandbox style campaign.
The games maps are hexbased (like you might expect), and while the resolution is fairly low (25 miles per hex) this leaves plenty of space for the GM to fill in his or her own details. I'm especially fond of the Diagram dungeon - which captures a lot of the coolness of an oldschool grid-drawn dungeon while avoiding it's inherent complexity and obsession with detail.
All in all, an excellent product I really can't recommended enough.
[5 of 5 Stars!]