I just finished reading the Pathfinder Chronicles book/periodical Dark Markets: A Guide to Katapesh. Katapesh is a part of the Pathfinder setting, set on the eastern coast of what is loosely fantasy Africa. It's a relatively wild place, famous for it's slave trade and drug trade, and features a kind of "Arabian Nights" feel to it, or possibly something akin to the feel of Morocco during the movie Casablanca, although part of that could be the subtle similarities between the name Katapesh and Marakesh. The quote above (from Obiwan Kenobi in the first Star Wars although hopefully you didn't need me to tell you that) applies quite well to Katapesh, (which is both a nation and a city) but, for that matter, it applies well to most fantasy cities, starting with the first famous fantasy city, Lankhmar, going on down through Greyhawk, Camorr, Freeport, and more. For that matter, Paizo have themselves now given us three differently themed "wretched hives of scum and villainy" in urban fantastic form, Korvasa, the devil-worshiping city that's gradually falling into decay, Absalom, the "center of the world" that's much more traditionalist in terms of what fantasy conventions and tropes it uses, and now Katapesh.
As I said, Katapesh is both a nation and a city; an overview of the nation takes up about the first 25 pages, an overview of the city takes up the next 25, and the last 12-13 pages or so cover a big collection of plot hooks, a new prestige class, some rules for pesh addiction, a few spells and feats, and a handful of monsters and animals. The nation is largely desert and savannah, and the city is old, decadent, corrupt, and... like I said, pretty Lankhmar-like (which in turn resembles Cervantes' version of Seville... I guess there's no stopping a good idea.) Savage creatures like gnoll slavers (and worse) inhabit the wastelands, making them dangerous to the hardy pesh farmers and caravans that cross the region. There's a lot of possibility for adventure laid out here in the boonies of Katapesh (making the fact that I'm also reading Sandstorm intriguing, because it's a great mechanical counterpoint to Katapesh's "fluff").
I'm a huge sucker for urban intrigue, though, so I found the section on the city of Katapesh more my speed. The relatively lawless nature of the city (unless you disrupt trade, which is the only real taboo) makes it the kind of setting I could spend several entire campaigns exploring, no doubt. Spending a little bit of time discussing pesh, the highly addictive and dangerous drug that is the main export (illegally, mostly) of Katapesh was also quite welcome. It envisions a society in which the (relatively) casual use of a drug that's known to be quite dangerous is seen as fairly normal, and why characters might want to gamble their fates on drug use for certain short-term benefits. This makes the drug integral to the setting, to an extent, rather than an afterthought; something you can really use. Although drug use is a fairly heavy, serious theme for an RPG, it does give the setting a dark, gritty, and semi-realistic (verisimilitudinistic, more accurately) feel that few RPGs explore.
I can heartily recommend this sourcebook, especially if you like picaresque sword & sorcery that feels an awful lot like Fafhrd and the Gray Mouser.
Now that I'm done with it, I'll probably slow down a bit (I've been simultaneously reading two RPG books at a time, and making notable progress in only one of them.) So rather than replace this book with another Pathfinder Chronicles volume, I'll finish Sandstorm and then move on from there.