Definitely not one of his best, but good nonetheless. If you're a fan of Frank Herbert, you know what to expect. This time, the question, "Who Rules?" is given from an ecological perspective.
Fans of Dune
will see familiar themes and ideas: ecological balance, adaptation, subtlety in using language, early runs at "The Voice." It's a short book that does some interesting world-building and mystery. The ending, while some people criticize as short, makes complete sense to me if you understand the answer to the question, who rules?
Students of Frank Herbert will see some lines and ideas later in books such as Destination: Void
, God Emperor of Dune
, and Hellstrom's Hive