Re: Should I warn them???
I think it was hamstrung by the sheer number of directors they had. David Lynch is a great director but was joining a half-finished film that had run out of ideas and was massively over-budget. Add that to some pretty wooden acting (whoever it that plays Paul is terrible - but Patrick Stewart as Gurney is excellent) and the film never really works. It happens all the time with films stuck in 'development Hell' and with Dune, it was always very ambitious for its time and needed clear direction.
I don't think the 'Dune' story has aged well due to our increasing knowledge of Islamic stories in the West (if you take 'Dune' to be an Islamic allegory, which I certainly do in parts) but there's no reason why a much better movie couldn't be made.
Interestingly, Harrison Ford never considered Deckard a replicant. He is a replicant, dammit but it's one of the reasons Scott and Ford fell out when making the film. I can't imagine it was easy to shoot, either. That was an ambitious movie. I see CGI used really badly in more recent films and always cite the 'city-scape' at the beginning of Blade Runner as one of the finest examples of using miniatures for superior effect. It just looks better!