I meant to write this up last year, but completely forgot!
I picked up The Art of Dragon Age: Inquisition a while ago. I knew it would contain spoilers for the game, so I kept it safely locked away until after I finished my Aztar game, then thoroughly read through it. It's pretty cool! I tend not to be much of an art book guy, but I'm willing to indulge for some of my favorite stories, and it's particularly intriguing to see all the hints and references to other ideas that were considered at various points during development which didn't make it into the final game.
There's a small amount of overlap with the content in The World of Thedas, like drawings that show typical outfits in various Thedosian nations (Ferelden furs, Orlesian masks, Tevinter black). The overlap is pretty minor, though, and the vast majority of stuff in here is new.
One particular thing I noticed was the War Table. There's some great concept art in there which shows some ideas which were fully developed from early on, like the enormous slab of wood which forms the War Table. But, there also are a lot of sketches that show various iterations of the War Table and imply that, at one point, it was possible to "evolve" the table. There's a concept for a table filled with tons of little drawers and cabinets, for the micro-managing Josephine; a sinister table with hidden compartments and poisons, for the underhanded Leliana; and a martial table supported by trophies, reflecting Cullen's preference for straightforward applications of force. The accompanying text briefly describes how at one point they thought that the table would reflect the approach you most often took on your missions. That's especially interesting to me, since it implies a different design for the War Table that probably did not include limited application of advisors over periods of time. In the current (shipping) game design, you always want to have all of your three advisors deployed, and thus will consistently be using a mixture of approaches. It seems like in earlier concepts, you might be able to, say, always follow Leliana's suggestions.
The book also brought my attention to some things that I had overlooked during my game. One big example here was the puzzle tiles in the Temple of Mythal. The book makes clear how the artists and designers went to great lengths to figure out how such a system would actually work, and came up with a mechanical design that would let them "light up" in reaction to pressure. I'd totally missed that, though, and just mentally filed it under the "magic!" category. In my second game as Visaas I paid a bit more attention, and had some more appreciation for all the work they put into this.
A lot of the book is devoted to character concepts, from rough pencil sketches to more fully-developed realizations. For example, there's a great spread on some concepts they tried with Morrigan, including some really interesting takes that featured her with more of a hunter look. It's a really cool take on an existing character, and reinforces the idea that she's been on the run for years. They ended up with a simpler update to her Origins design, which is fine, but it's great to see that this wasn't a matter of laziness, but rather the result of some concerted thought and effort.
I'm glad that I splurged on the collector's edition. It isn't an essential book, even for hard-core fans, since the lore is pretty light. However, it is an absolutely gorgeous book stuffed with fantastic artwork, running the gamut from loosely sketched storyboards to beautifully realized landscapes. It provides a surprisingly deep amount of insight into the work that goes into making a video game like this, showing how ideas are sparked and evolve and solidified, as well as some of the possibilities that were considered and eventually discarded over the long course of making the game.
I tossed together snaps of a few representative pages in an album here if you'd like to check it out, though I should warn you that my crummy camera doesn't begin to do justice to how vibrant the pages look. The collector's edition is sold out, but I believe that the hardcover edition is the same book, minus the slipcase and signed prints, and at a fraction of the price I paid. If you're looking for some more Dragon Age goodness to tide you over until some Inquisition DLC arrives, this might fit the bill.