What is it lacking? I'd say a sense of wonder, but also a sense of horror. It's surprisingly mundane in its presentation, which, in one sense, may have been the point, but this is where relying on existing tropes does matter. We're very conditioned to find the extremes when we read about new races, civilizations, and so on. This doesn't give that sense of revelry throughout, and, if that was in fact the point, it's simply not direct enough to be clear or engaging.
I just felt disappointed. So much promise unfulfilled on this one. I can't imagine recommending this to anyone other than really solid fans of his.