I see Wells has writing credits on Stargate tie-in novels, and the setup of this book is strongly reminiscent of the Atlantis setting. (The moving-into-abandoned-city scenes are dead on, and the missing artifact might as well be a ZPM.) However, the author indulges her love of splendiferous settings -- this world really has Mieville-esque depth of detail and variety, without the ick quotient; maybe I should say Whelan-esque or Froud-esque -- and the story winds up closer to sword-and-sorcery than anything else. Only without the swords. When your protagonists are shape-shifting flying lizard beasts, they don't need to muck around with sharpened metal sticks.
As before, there is no world-spanning, turning-of-history crisis; this is still not epic fantasy. The scope is strictly a city, another city, and the city they fly past on the way between. The author could keep this up for as many volumes as she wants, or she could stop here; that sort of series. We do get character development, but it's in the that-sort-of-TV-series way.