The departures are forgivable if it helps adapt the script to the screen. But there's too many other flaws.
It's never explained in-movie why they have lasguns, but don't use them.
Why did it take feyd rautha to come up with the idea of using artillery? Isn't "bomb the enemy's base" basically a starting strategy?
Why did they only use sandworms on the last battle?
Why did nuking the mountains throw giant boulders for miles but not kill everyone from radiation and shockwave?
Why can paul get stabbed X times and not need any rest or medical attention?
What's the point of any conflict in the movie if the bene gesserit basically call every shot ever anyway?
It's a really good movie as long as you don't ask questions. Reinforcing my theory that the main problem with modern Hollywood is always writing.
I think they briefly mentioned the laser gun issue with shields in the first movie. It never explained why people were using lasers all the time. There was a scene in the first movie where one character was flying out of the city to get away. They were firing lasers at him which would seem stupid if he had shields on the craft. Destroy the whole city.
They compressed the timeline a great deal in this version so Paul and Chani's relationship doesn't get much time. Paul was with the Fremen for 2 or 3 years.
The Fremen were the greatest fighters in the universe from the start in the movie rather than learning the weirding way from Paul and Jessica to make them even better. Again, no time for that to happen.
In the book, Paul knew how to make rockets and other weapons the Fremen started using. He also had been training at guerilla warfare tactics and advising the Fremen in their raids on the Harkonnen. That was part of what gained him respect such that he was recognized as the leader.
There is probably other stuff about the movie I may have missed. Since I have read the book, some of the back story is assumed.
