So......I bought the Dragon Empires Primer PDF after getting the Gazeteer and finding that it left out some info on the Dragon Empires that would be included in the Primer. Like kitsune racial feats, and regional traits. What a waste this turned out to be.
Not only is most of the Primer just condensed or copied descriptions from the Dragon Empires Gazeteer (meaning I basically paid twice for most of the Primer's content), but there's hardly any new or useful info in the Primer for anyone who already has the Dragon Empires Gazeteer. Only 2 regional character traits for each country/region, 3 kitsune racial feats (all based on changing to fox form and back, quickly; nothing for their spell-like abilities or other racial traits), 1 bard archetype (Lotus Geisha), 1 samurai archetype (Sword Saint), 1 ranger archetype (Yokai Hunter), 1 witch archetype (White-Haired Witch), 10 new combat feats (only 1-3 of which are any use to non-monks....and 5 of the new feats are worse than core feats or just fairly pointless), 1 new samurai order (for evil samurai, and nothing new or special about it), 1 new sorcerer bloodline (the Oni Bloodline, which has a standard sorcerer skill as its bloodline class skill), 1 new wizard school (the void elemental school, which is a bit odd and requires both the Advanced Player's Guide and Ultimate Magic since some of its spells are only in those sources), 1 new wizard spell, and 2 pages describing Honor mechanics for the Dragon Empires as an optional rule.
The new material only occupies around 9 pages, and at least 1-2 of those are worthless to DMs. All in all.....the Dragon Empires Primer just isn't worth it for a DM, unless money and value are non-issues to you. Just get the DE Gazeteer PDF, if even that, which is only somewhat more detailed but more useful to DMs.
Players, at least, will get enough out of the Primer to at least make some characters hailing from the Dragon Empires, but only just. The 4 class archetypes are interesting enough and should be capable enough in a Dragon Empires campaign (perhaps the Jade Regent Adventure Path), though the Lotus Geisha and Yokai Hunter and some regional traits are unlikely to be as useful in some other parts of Golarion. The Void Elemental wizard school is neat and Call the Void is a cool spell, but with an error (it says victims can't cast spells with somatic components, when it should say verbal components, since victims can't speak in the airless void), and you'll need the APG and Ultimate Magic if you want to use its other spells. A few of the combat feats are actually useful, like Sleeper Hold, but most are weaker/more-limited than core feats.
For starters, I love OA campaigns and was really looking forward to the Dragon Empires material allowing me to run such games in Pathfinder.
So....I made the mistake of paying almost 25 bucks for a print edition of the Dragon Empires Gazeteer (nearly 5 bucks in shipping and handling for this thin little booklet is excessive). Not only is it thinner and (through S&H) more expensive than 2E or 3E softcover supplements were (62 pages of actual content, if I count the inside-cover geographical map, relative to the 127 black-and-white pages of a 2E splatbook or 95 B&W pages of a 3E splatbook), but it contains only the briefest descriptions of each country, a few organizations, some deities, core races, Tian Xia humans, and the five new races.
The timeline (2-1/2 pages) and much of the "Life in the Dragon Empires" chapter are at least reasonably descriptive. But still only a cursory look at the continent of Tian Xia and its history/cultures. For a book whose introduction describes Tian Xia as more than 5 times the size of the Inner Sea region, it suffers rather badly from compressing a continent's worth of info into a few dozen pages of scant overview (roughly a fifth as many pages as the Inner Sea World Guide, and what I've heard about that book leads me to believe it's only slightly better than the DEG in descriptive content).
There's a very basic geographical map of Tian Xia and a geopolitical map that only really shows the capitols and borders. No zoomed-in maps of the individual countries/regions and their features, and no cities or the like beyond capitols. Each country/region of Tian Xia gets a 1-page description or less, with nice but useless illustrations stealing space away from some of those pages. Only a few actually show leaders or locations within the country/region described on the page. Others show monsters that must be detailed in other books like the Bestiaries. They're interesting places but still terribly lacking in detail for an actual campaign in any of these regions.
There are a few pages of scant description for major deities of Tian Xia, such as Daikitsu the Lady of Foxes, including a few Golarion deities like Irori and Shelyn with notes regarding their worship on Tian Xia. Each deity gets hardly a paragraph, with a few useful bits of info beside their holy symbol and domains. The Moon subdomain is given a sidebar, but nowhere is the Moonstruck spell described; you need the Advanced Player's Guide for it. There's 1-1/2 pages describing philosophies and 1-1/2 pages describing some factions in the Dragon Empires. The 5 races get a page each (1/4th illustration, 3/4ths description). For some reason, you need the Dragon Empires Primer (not free) in order to view the kitsune's 3 or 4 measely racial feats (1 for fox form, 2-3 related feats). Core races get a paragraph each regarding their place in Tian Xia (generally as solo wanderers), while human ethnic groups get 2-1/2 pages total.
All in all, I'm not even sure if this is enough to run the Jade Regent AP well, let alone make my own campaigns in the Dragon Empires.