Wait for the director's cut. If you're a non-Dune fan, I believe there is too little explained for it to make sense for average film viewers. If you're a Dune fan, you'll be confused as to why many parts of the plot or parts of character development are omitted.
As a fan of the book myself, I was sat thinking "How are people new to the universe going to follow this?" The film isn't difficult, but there's too much missing for the average person to be invested. It feels more like a visual accompaniment to the book rather than a standalone work. When I saw that the film was only going to be "part one", I thought they would spend the 2.5 hours really establishing the universe. Villeneuve's lingering scenes unfortunately prevent this in the run time.
It's technically a brilliant film, but I seriously believe that there were a lot of scenes cut from the theatrical release. There must have been more dialogue scenes that help advance the story that were omitted in favour of more time being dedicated to the action scenes. Despite the length of the film, it also feels like the actors were underutilised - I think this has to be a consequence of many scenes being cut for cinemas.
I really hope a director's cut is in the works, because I would like this franchise to do well.