I picked up a copy of the Dune RPG book at GenCon 2000 (? was it 2000? my memory fails...). I didn't know anything at all about the game when I bought the rulebook, and it wasn't d20, but Dune has always been one of my favorite books/stories since I first read it as a wee lad.
I was less than thrilled. I'm going on memory here since I haven't looked at the book in a while, but there is virtually nothing in the book about Arrakis or Fremen, the 2 topics I was most interested in adapting for my D&D campaign. The book focuses primarily on the socio-political structure of the known universe, with emphasis on the Ruling Houses, and the factions such as the BG and the Guild.
I guess there's a fair amount of background info in there that a DM would find useful in running a campaign in the Dune universe, but there was very little that was immediately adaptable to a D&D game... which is almost always a primary consideration in my gaming purchases.
I recall that there was a supplement supposed to be released a couple months later that did focus on the Fremen, but LUG tanked and the planned supplements were never released... particularly unfortunate as they were already written.
p.s. sorry, Florin, I haven't picked up FS d20 yet so I can't comment on their Noble class.