It is close to 35 years since I read "Destination: Void" at university. But it is still among the best ten books I have ever read - and I have read many thousands since then. In fact, it played a large part in my decision to enter the fledgling computer industry back in 1970. It must be admitted, though, that the book is deliberately aimed at a rather limited audience. In a world of commercialism run wild, I find this rather refreshing.
Herbert does not complicate matters wilfully, but on the other hand he makes no concessions whatsoever to his readers' ignorance. He assumes that they are interested both in technology and in the problems of existence, consciousness and religion. There should be plenty of people like that out there, right? Maybe they are all too busy doing useful work to read SF novels!
The upside is that Herbert is a real expert, and even allowing for the 30 years that have elapsed (a huge chasm in terms of technical progress) this book is vastly superior to the schlock that passes for SF today. The Tin Egg has the authentic feel of an experimental interstellar spaceship, whereas starship Enterprise is basically a flying playpen.
As for the science, it isn't too clear just where the facts leave off and the fiction sets in - and that is good, too. Suffice it to say that we still aren't any closer to cracking artificial intelligence yet, let alone artificial consciousness. (See Heinlein's "The Moon is a Harsh Mistress" for another approach to the latter). So Herbert's speculations have hardly dated at all.
Personally, I rate "Destination: Void" as Herbert's best book, ahead of Dune, The Dragon in the Sea (Under Pressure), Dune Messiah, and The Dosadi Experiment. A matter of taste, I guess.