Some parts of the first book dealing with environmentalism are great, but the rest is kinda meh. My main problem is that the Dune Universe seems too small: almost all important events in the Universe happen to the same couple of main characters, and almost everything that happens to them is very important to the Universe.
There's a part in Dune Messiah when someone mentions a certain event happens to a very large number of people; they could have made that number 100x larger or 100x smaller and the result would be exactly the same.
I read that God Emperor is good, so I'm trying to decide whether to start the third book or just cut my losses and abandon the series.