Crawford says it’s the biggest yet, with 7 classes (Experts: Ranger, Rogue, Bard; Priests: Cleric, Paladin, and Druid; and Monk confirmed), spells and weapon mastery tweaks, capstones back at lvl20 (epic boons will be pushed to another UA), and subclass progression reverted to the 2014 cadence after lvl3. Notably, rogues are seemingly getting another feature at lvl5 to make up for the fact that they get very nothing from their subclass between 3 and 9.
I honestly like that some choose their subclass at a different level. For the paladin especially it feels really appropriate.