Synopsis of the two Dunes:
Be prepared for a bit of woke bullshit in the new movie. The new movie is still good, but they feel they have to use a certain ethnicity for certain roles even though that makes it contrived. In the new movie Paul is started off at a much younger age (teenager) than in the old movie. Obviously the special effects are totally on point in the new movie. The big picture emperor stuff is introduced earlier in the new movie and things are spelled out somewhat more in the new Dune movie whereas Lynch assumed people actually still read books when he made the old Dune and so he expected the audience to be familiar enough with a lot of the background having read the Frank Herbert books. That is, the new movie does more spelling out but not excessively so. For example in the new Dune Paul has these educational media to glean background information about Arrakis such as it's strategic relationship to the empire, details about the sandworms and the Fremen. It only has this on one part of this first film so it doesn't detract much from the new movie. The Harkonians were depicted more as elite cruel soldiers in the new film versus the old where they had all the heart plug stuff more emphasized. In both films the Harkonians are quite cruel of course.
Paul's mom seems a bit more goal-oriented in the new movie (first duty to witches rather than family) and seems to play a bigger role in the new movie if I remember how much of role she had in the old movie correctly.
In short, as you stated, you will like the old movie better (I did too), but the new movie is very solid and it is not stand alone, there will be another couple of movies to tell the whole story rather than the one in the old Dune.
Ratings: new movie 7/10
old movie 10/10