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 play with 2 groups and one group does a main campaign and then smaller campaigns every n weeks so that way the DM has time to prep, adjust plans, and it’s lower stakes if someone misses. Add in the occasional one shot or two and you churn through the interesting subclasses quickly.