I like this version, it has a lot going for it - the extra time allows a lot more depth than the film. It is not perfect, however, I did not particularly like the portrayal of Paul as a spoiled brat, perhaps it's just not how I read the book, but it felt like an unnecessary deviation. Some people have also complained about the production values - obvious sets and etc. That is certainly true, but as far as I'm concerned they did the best with what they had and made good use of it. If you're looking for a high-budget all special effects bonanza you're wasting your time. If you're looking for a (fairly but not totally) faithful account of the book Dune, then by all means watch it. However, for completeness watch the film as well - both have their strong/weak points and it is well worthwhile (if you're a fan) to take the time to explore both versions.
So to sum up:
Plus points
More story than the film (because it's longer), decent acting (mostly), fairly faithful to the book, different pronunciations (no idea which is right), the serialised nature of it means you can sit and watch some without watching all at once (the full version is around 6 hours).
Minus points
Some costuming issues (the Sardaukar look like chefs imo), some obvious sets/special effects, perhaps too long for the casual viewer (or sci-fi widow/widower), Paul's a bit too much of a brat.