I picked up DCC 35 and am now suffering from buyer's remorse. I've picked up other DCCs and use them from time to time, but the world itself has turned out to be ho-hum in my opinion.
For the style of gaming it advocates, I'd much rather use a setting like Greyhawk. My players are already familiar with the core D&D pantheon and it has the same vanillia-fantasy flavor to it as DCC setting. Now granted we hadn't run/played Greyhawk for years and years like some people have on these boards, so there's still that feeling that almost anything can happen. Reading through the "Savage Tides" series has given me good reason to dive into years worth of material.
Here's the breakdown of what you get in the DCC 35 box set. First is the Gazeteer, which I guess is for both player and DM, offers descriptions of nations and cities, geographic features, holidays and calendar. The DM Guide gives you a detailed origin of the setting, full description of pantheon, setting specific feats and equipment, description of 0 level adventures, and a list of possible "Adventure Paths" based on DCC modules. Four maps - three of which interlink making one big honking uber-map, and the fourth is a clouded "Players Map" which is essential the middle map of the set of three.
Reading the individual nations, the majority of "civilized nations" in the north, where the major human empire (Crieste?) has been crumbling for several centuries, allowing outlaying areas to strike for independence. There are several other interesting nations, including major Elven and Dwarven holdings. To the south is your "ancient Egypt" and Africa setting, and to the west is your Meso-American setting complete with Aztec-like people and Nagas.
I had to read several of the counties with a jaundiced eye. For instance there's a huge business in slave trade, with centers in at least a couple of cities. But there's no mention where these slaves are coming from. Usually there's wars going on and people are being captured and sold off. But from reading descriptions of other nations, every place on the map seems to have large amounts of "badass" qualities. Maybe I should read through it another time, but I think I'm just going to sell it off instead.
Needless to say, this doesn't appeal to me as say, Eberron or Blue Rose, or my own favorite Kara-Tur.
After all, when it comes down to it, you're really looking for a map, some interesting cities fleshed out, and perhaps a few power groups defined. You said yourself you already have races and cultures, now you just need somewhere to plop them down and connect the dots. I don't think you need to shell out big bucks to do that.