The thing that really made me love this book was the chapter that introduced the dolphin captain, Creikeiki. In a few short pages, Brin paints a picture of a weary, courageous leader, a poet, a genius, a wise and gentle soul. By the end of the chapter I loved Creideiki more than I've cared about most other fictional characters, with the possible exceptions of the Opera Ghost and Ender Wiggin.
Other than that, the novel is a very good sci-fi action story. Lost in space, out-of-order and under seige, out-gunned, out-numbered, etc. It's a fun read and all the other characters are three-dimensional and well-developed. I'd give it five stars if the rest of the writing was as fantastic as that first chapter about Creideiki, but it's still high-quality. Brin is a rising star in the world of science ficiton.