Since this book contains two seperate and unconnected stories, it makes sense to review them seperately.
The first is "Cuckoo's Egg", a hugo award nominee from 1985, and my first ever story by this author. I'm impressed. A new and interesting twist on a common SF theme with a continued sense of unfolding mystery from start to finish. The story stands on it's own but leaves itself wide open for a sequel or even an ensuing series but, apparently, this opportuity has not been exploited. (4 stars).
The second story is "Serpent's Reach" is the longer of the two although it need not have been. It takes far longer to get going, spending a large number of pages establishing the protagonist's background, the complex social and political systems, and the human relationship with the hive mind alien beings native to the system in which the story takes place. Eventually though the story does pick up and it draws you into the curious scenario. Unfortunately, the resolution is somewhat chaotic and unsatisfactory. (3 stars).
In both stories, the extensive world building and attention to detail stand out as being among the author's strong points. In the first, shorter story it seems almost wasted, like more should have been done with it. But in the latter, it seems that it was at the expense of the story itself and made if far longer than it need be. I can see why much of her works are series and I imagine they would work quite well; giving the author plenty of room to develop worlds and societies but not requiring her to drag out the story lines excessively in doing so.
I look forward to trying some more of her work at some point, recommendations welcome!