Please take this review with a grain of salt, as I'm listed as the editor and one of the authors of this book :)
This version of the book provides something essential that has been sorely lacking from every other version of the book to date, including (I regret to say) the one that I was the lead developer of: clear-cut statements of where in the real world each fantasy location is equivalent to. This may not seem like a great deal to the first-time buyer, but as someone who followed the setting from its OGL debut and its first 4e incarnation before getting involved in its development, not having to rely on vague and often-misleading maps to determine where everything is (I discovered during editing that I had been dead wrong about where quite a few places were for years) is a great boon. Additionally, the developer commentary is a great feature that I wish could be found in more RPGs, and would certainly be of value even to people who have experienced the setting in its other manifestations before (it was certainly fun to write my bits, but even more so to read the others).
13th Age is not my favorite system by any means - I find it a bit of an awkward kludge between 3e and 4e, with a few interesting unique mechanics, and unfortunately, this version doesn't engage as much with those mechanics as I would like (but I promised to stop completely rewriting the mechanics during editing after 'Neurospasta,' so I'm as much to blame as the developer is). It does, however, polish a lot of the mechanics from the 4e version and is far less mechanically bloated by comparison. It also introduces some interesting new mechanics, all of which are optional (something that I personally find very welcome, as having variant mechanics forced on me by the game's design parameters is something that greatly annoys me as a player and a GM). Given a choice between playing this version and 4e, I would choose this version even though I prefer the 4e system.