Dune was written in 1965, and yet its themes of political positioning, religious zealotry, and environmental disaster are as relevant today as they were then.
Do NOT go into two movies totaling five and a half hours and expect the entirety of Herbert's masterwork to be done flawlessly. There's little to no mention of the Landsraad, CHOAM, the Butlerian Jihad, or Ixian tech. Book-important time-jumps are eliminated in favor of keeping things going. Certain characters aren't going to get hours of exposition to explain to you what they're doing and why. Motivations are either understood via reading the novel, or else they're missed entirely.
DV has still managed to do the un-doable.
He has brought a sort of visual "best-of" highlight reel to one of the greatest works of fiction ever written.
If you have NOT read Dune, go do it. Then see the movies.
If you have read Dune, and enjoyed it, see the movies.
If you read Dune, and didn't enjoy it, then why the heck are you even considering watching the movies?