I can't blame those of you who are clamoring for a copy, because it must seem like a very exciting idea for a book. However, the articles in the Encyclopedia vary widely in quality, as they were written by a motley collective of people at the Prof's university. Their enthusiasm is fun, but their ideas don't seem to quite gel with Herbert's work in some cases. In other words, a lot of the writing doesn't feel quite 'Dune' and the illustrations are mediocre (you're better off with your imagination or Lynch's baroque artistic vision). At times, it reminded me a little of -- and this isn't praise -- fanfic.
Still, Herbert was apparently delighted by the enterprise and agreed to its publication, which (as someone has pointed out) is more than can be said for the 'prequels.' However, keep in mind that the Encyclopedia only covers material for the first four books- the puzzles of the last two get no Herbert-approved elucidation (rats!).
It would be nice if they'd reprint the Encyclopedia for the curious (although I don't see it happening, now that the prequels are offering a lucrative competitive vision of the past), but it'd be nicer if they'd just print Herbert's notes in their rawest form so that we could just deduce for ourselves what the hell was supposed to happen next.