Well, I'm not going to give up a fancy stout without some sort of description.
Well it's a set of three books, Southlands Worldbook, City of Cats Citybook and Adventure, and Southlands Player's Guide I got for supporting the Southlands kickstarter.
They are simply the best 5e products I've ever seen, the paper and cover material quality alone simply blows WotC crappy quality away.
They are 3 books instead of trying to cram all of it into one like WotC and it leads to a vastly superior product.
This is the kind of product the Forgotten Realms should have gotten and never did.
No WotC product had me just reading for hours at night for days like these books did.
The setting is rich with a mixture of plot hooks and details and unique cultures and mechanics and races, etc..., you can just loss yourself in the setting the way you simply can't in WotC 5e setting books (to be fair EGtE, VRGtR, and E: RftLW are fun reads, just not as good as the Southland books).
One unexpected thing is that the high paper quality of the Southland books left me disguisted by the poor quality of WotC's books. WotC is supposed to be the industry leader for **** sakes.
The art is absolutely gorgeous and vivid.
It's simply the most Immersion 5e setting. I don't want to spoil things. It's based on Fantasy Africa & Middle East, although there are some other things too.
It does reference other Kobold Press books for creatures too much and there is a disparity in demographics listed for the City of Cats between the Worldbook and the Citybook (personally I'd just mix the highest number of each listed race in each listing to come up with a final number, it's more fun that way), and Aasimar really should have been in the Player's Guide as they are a very important race to the setting, and having female only priesthoods is something I'd ignore, but other then those complaints it's a great set of books. Just wish the exchange rate and shipping to Canada had been cheaper.