Races of Stone was a good book and brought hope to this series. I personally thought the new race (Goliaths) was good, but that it took up a little too much space. From all that I've heard Races of Destiny has the same problem, only to a much greater extent. Illumians become the focus and everything else is piecemeal. That leads to the real problem with Races of Destiny: it simply attempts to cover more races and offshoots than a book its size can actually hold. As a result the new race becomes the center of attention while the familiar races simply serve as filler.
Having enjoyed Races of Stone so much I had high hopes for Races of Destiny, but I also saw it as the most dispensable of the three scheduled volumes in the series. If Races of the Wild gives too much space to the bird-people, I suspect it will fall as well. There is still some hope in me that it will turn out at least as well as Races of Stone and if it manages that I'll be more than pleased.