I bought the Dune RPG back when it first came out, and in a week, I saw that it was selling for $90+ on eBay. So, I sold my copy.
If you've got specific questions about it, I'll try to answer them for you.
From my initial impression, it was a pretty well thought out game. I liked the rules system, and there were lots of universe-detailing data on the Houses and planets and such.
I'd say the book was worth it if you are dying to play Dune (specifically Dune).
With a little bit of elbow grease, though, you could easily use the Traveller rules (especially the CT rules) into a Dune game.
I'm sure you know that Traveller was originally designed as a non-specific setting science-fiction rpg.
It wouldn't be too hard at all to change a few skills and alter a couple of careers to end up with a game in the Dune universe.
One other item you might be interested in, if you're interested in Dune, is the Fading Suns RPG. That game IS Dune, just under a different title.
What I mean is--it's very much like Dune. The atmosphere. The backstory.
I'm pretty sure the original (pre-d20) version of the game is out of print now, and you should be able to find it for fairly cheap.
That game could easily be used/converted into a Dune game. You could use Fading Suns rules, or you could just use it as background, using Traveller for the rules.
If you're interested in Fading Suns, there's a d20 version of the game too.
But, if you want to lay out the bucks for the Dune rpg, I don't think you'll be sorry. From what I saw, it was a good game.
Like I said above, if you've got specific questions, hit me with 'em.
I'll try to help.