It's better to try to remake bad movies or flawed-but-interesting movies instead of great ones. 1984's Dune is a silly mess, a lowlight in David Lynch's otherwise praiseworthy career. Director Denis Villeneuve enters on a hot streak, having made three good-to-excellent films in a row (Prisoners, Arrival, Blade Runner 2049). But his take at Dune feels like it's missing something, even though it's pretty to look at (you should definitely see it on the big screen instead of HBO Max).
The plot of Frank Hebert's book Dune is too long and convoluted to explain in a brief film review, but the simplest explanation is that there is an intergalactic effort to mine the valuable mineral called spice on a distant planet. An evil baron (Stellan Skarsgard) maneuvers to kill the benevolent leader (Oscar Isaac) asked to oversee the spice planet. The leader's son (Timothee Chalamet) might have magical powers and be a fancy term that translates to "the one."
While 1984's Dune tried to cram all of Herbert's massive novel into one 2-hour film, Villeneuve made a 2.5-hour film and is hoping to make a follow-up (Warner Bros recently greenlit the sequel). The problem is the new Dune indeed feels like it ends very abruptly. The first three films of the Star Wars trilogy feel like parts of a whole, but each film works on its own individual merits. Dune does not. It doesn't feel like it has a third act. The pacing also drags.
Full disclosure: I've never read Dune, so maybe the source material isn't my cup of tea. If you are going to see it, see it on a big screen where you can appreciate Villeneuve's visuals.