60 FPS support is included among the features, as well as quick save functionality and curated add-ons (megawads, as Bethesda puts it). This includes episodes and megawads made by the community, all of which can be found for free in the main menu of both games, with Bethesda soon opening suggestions for new content to include in the future.
The original games ran at 35 FPS, so 60 FPS is a big jump up too, and the quick saves work by pressing R/R1/RB while paused in either game, with L/L1/LB on the menu loading up that spot again.
Options and quality-of-life settings have also been added too, including an improved level select function, added aspect ratio and brightness options, and more.
Are you going to head back into Doom or Doom II?