Czerneda has created one of those wonderful endings to a book where you dread reading the next paragraph but are compelled to keep reading every last word. No matter how tempting it is to skip ahead to reassure yourself of the outcome, I can pretty much guarantee that you won't. I would recommend that once you're into the last hundred or so pages that you be prepared to read without stopping. You may to take an occasional pause to get your heart started again, or to remember how to breathe, but that's about it.
Species Imperative has to be one of the first hard Science Fiction series I've read that manages to not get caught up in the bang, bang, shoot, shoot to the exclusion of characterization. Julie Czerneda has created the miraculous mix of humanity (or speciesity?) that characterizes all great fiction. Combined with the best elements of a true adventure story, generous dollops of leavening humour, and exotic locales, it sets a new standard for other authors to match in this genre.
Species Imperative: Regeneration is a fine conclusion to a great series. The only warning I would give is not to start reading the first book without having access to the second and third. You are not going to want to stop once you begin.