Not that I have all the cetacean field guides available, but as soon as I read this book via my library loan, I knew that I wanted the book. For a starter, it included the newly established Orcaella heinsohni (Australian Snubfin dolphin) as a separate species to Orcaella brevirostris (Irrawaddy dolphin). Then, it also provides me the complete ID guidelines for the dolphin species I'm currently studying, i.e. Spinner dolphins, Stenella longirostris, including the existing four subspecies (Hawaiian, dwarf/Southeast Asian, Eastern, and Central American spinners). It also specifically notes the dwarf minke whale (Balaenoptera acutorostrata) as a subspecies/allospecies aside from the Northern minke whale (Balaenoptera acutorostrata) and the Antarctic minke whale (Balaenoptera bonaerensis). I've bought it now from Amazon UK, and the book is highly recommended!